BACF - Basics In Computer Fundamentals

Peripheral Component Interconnect (PCI)

2008-08-09T00:02:00.001+05:30

(PCI) A standard for connecting peripherals to a personal computer, designed by Intel and released around Autumn 1993. PCI is supported by most major manufacturers including Apple Computer. It is technically far superior to VESA's local bus. It runs at 20 - 33 MHz and carries 32 bits at a time over a 124-pin connector or 64 bits over a 188-pin connector. An address is sent in one cycle followed by one word of data (or several in burst mode).

Byte and bits

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Just as a word is made up of letters, a byte is made up of bits. While words have a variable number of letters, all bytes have eight bits. A bit represents a positive or negative electric charge. The computer interprets these electric states as either the digits 0 (negative charge) or 1 (positive charge). These are the only two digits the computer can understand. Because of this, computers work on a binary number system, instead of the decimal system we are used to. The word bit stands for binary digit.
The computer interprets the negative and positive electric charges as binary digits (bits), and groups eight bits together. The sequence of the eight 1s and 0s identifies one byte from another. There are 256 different possible 0-1 combinations the eight bits can make (2 to the power of 8 = 256), and so a computer can identify 256 different characters. This is a sufficient number to represent all of the uppercase and lowercase letters of the alphabet, the digits 0-9, all the punctuation marks, a symbol used by the computer for a space, special characters such a * and I, other symbols used specifically by the computer, and still leave plenty of possible symbols for future uses.

8 bits = 1 byte

1,024 bytes = 1 kilobyte (K)

1,024 kilobytes - 1 megabyte (MB)

1,024 megabytes = 1 gigabyte (GB)

1,024 gigabytes = 1 terabyte (TB)

kilo- k 1000^1 1024^1 = 2^10 = 1,024
mega- M 1000^2 1024^2 = 2^20 = 1,048,576
giga- G 1000^3 1024^3 = 2^30 = 1,073,741,824
tera- T 1000^4 1024^4 = 2^40 = 1,099,511,627,776
peta- 1000^5 1024^5 = 2^50 = 1,125,899,906,842,624
exa- 1000^6 1024^6 = 2^60 = 1,152,921,504,606,846,976
zetta- 1000^7 1024^7 = 2^70 = 1,180,591,620,717,411,303,424
yotta- 1000^8 1024^8 = 2^80 = 1,208,925,819,614,629,174,706,176

Name	Abbr.	Size
Kilo	K	2^10 = 1,024
Mega	M	2^20 = 1,048,576
Giga	G	2^30 = 1,073,741,824
Tera	T	2^40 = 1,099,511,627,776
Peta	P	2^50 = 1,125,899,906,842,624
Exa	E	2^60 = 1,152,921,504,606,846,976
Zetta	Z	2^70 = 1,180,591,620,717,411,303,424
Yotta	Y	2^80 = 1,208,925,819,614,629,174,706,176

Use Google search as a Calculator

2008-08-08T23:52:00.000+05:30

Though its an old trick but many of my readers keep asking me to write about Google Tricks and Tips and this post is dedicated to them. In this post, i shall explain the process of using Google as a Calculator.

I use Google for almost anything these days, be it Getting more blogging ideas using Google, Using Google to track the movies playing in my area, checking out cricket scores or to get the local time of some place i have business in.

To use Google’s built-in calculator function, simply enter the calculation you’d like done into the search box as seen below in the picture. The picture below tries to compute the result for 5*9+(sqrt 10)^3.

Google Calculator

Google Calculator is pretty intelligent in terms that it can understand things other than the mathematical formulas and give you results. Try making a search for 100 miles in kilometers or 0×7d3 in roman numerals or speed of light.

Other good things to know

You can force the calculator to try and evaluate an expression by putting an equals sign (=) after it. This only works if the expression is mathematically resolvable. For example, 1-800-555-1234= will return a result, but 1/0= will not.

Parentheses can be used to enclose the parts of your expression that you want evaluated first. For example, (1+2)*3 causes the addition to happen before the multiplication.

The in operator is used to specify what units you want used to express the answer. Put the word in followed by the name of a unit at the end of your expression. This works well for unit conversions such as: 5 kilometers in miles.

You can use hexadecimal, octal and binary numbers. Prefix hexadecimal numbers with 0x, octal numbers with 0o and binary numbers with 0b. For example: 0×7f + 0b10010101.

The calculator understands many different units, as well as many physical and mathematical constants. These can be used in your expression. Many of these constants and units have both long and short names. You can use either name in most cases. For example, km and kilometer both work, as do c and the speed of light.

For more information on using Google Calculator, try reading Google’s Help Page.

Get news alerts from CNN on Gtalk

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To get news alerts from CNN-IBN on Gtalk, follow the steps below

1.) Add im@ibnalerts.com to your friends list in Gtalk.

im@ibnalerts.com

2.) Send Help for help on various news alerts available.

Help on im@ibnalerts.com

3.) Follow the instructions mentioned in the help message. For e.g., to get top news from ibnlive, send top.

Top alerts

4.) You can even subscribe to the alerts by following the help obtained after sending subscribe to im@ibnalerts.com

Subscribing to ibnalerts.

I am not sure but i guess even other Jabber clients should support this feature. If you have already tried this on other Jabber clients, do comment and share with others.

[How-To] Find out the location of person using your Wireless network

2008-08-08T23:48:00.001+05:30

If you have ever wondered about the possibility of your wireless network getting used for illegal purposes, you must consider using Moocher Hunter. Using Moocher Hunter you can identify the location of the person i.e. an unauthorized user using your wireless network. Its then upto you to either give him a stern warning of not using your wireless network again or complaining to the legal authorities.

Access Point for Wireless

MoocherHunter is a mobile tracking software tool for the real-time on-the-fly geo-location of wireless moochers and hackers.It identifies the location of an 802.11-based wireless moocher or hacker by the traffic they send across the network. If they want to mooch from you or use your wireless network for illegal purposes (e.g. warez downloading or illegal filesharing), then they have no choice but to reveal themselves by sending traffic across in order to accomplish their objectives. MoocherHunter™ enables the owner of the wireless network to detect traffic from this unauthorized wireless client (using either MoocherHunter™’s Passive or Active mode) and enables the owner, armed with a laptop and directional antenna, to isolate and track down the source.

Because it is not based on fixed or statically-positioned hardware, MoocherHunter™ allows the user to move freely and walk towards the actual geographical location of the moocher/hacker. And of course, as part of the free OSWA-Assistant™ wireless auditing LiveCD toolkit, MoocherHunter™ is also FREE for end-users to use on their existing laptops with off-the-shelf supported wireless cards.

In residential and commercial multi-tenant building field trials held in Singapore in March 2008, MoocherHunter™ allowed a single trained operator to geo-locate a wireless moocher with a geographical positional accuracy of as little as 2 meters within an average of 30 minutes.

Download MoocherHunter™ and the OSWA-Assistant™ here.

Remove Documents from Start Menu

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Open up your favorite registry editor. Navigate to

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer

Right-click on the right pane and select New, DWORD Value. Name it NoRecentDocsMenu. Double-click and enter 1 as value. To restore the Documents menu, reverse the steps by changing 1 to 0 or delete DWORD value.

Control Arrays:

2008-08-08T11:09:00.003+05:30

A control array is a group of controls that share the same Name, type, and event procedures. Acontrol array has at least one element and can grow to as many as elements as your systemresources and memory permit, and the size also depends on how much memory and Windowsresources each control requires. Elements of the same control array have their own propertysettings. Common uses for control arrays include Menu controls and groups of OptionButtoncontrols.Control arrays are useful if you want several controls to share code. For example, if you createthree OptionButton controls as a control array, the same code executes regardless of whichbutton receives the Click event.Eg. as the following code showsPrivate Sub optButton_Click(Index As Integer)' Index indicates the control that was clicked in the control array.picDisplay.BackColor = QBColor(Index + 1)End Sub

Arrays

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Introduction
These are described in your text in chapter 8. They are dealt with quite similarly to Pascal.
The lower bound (which can be found with the LBound() function if needed) of an array is the
lowest index (element number) of the array. By default it is zero - but you can change this
default to one if you use the Option Base 1 statement at the start of your module. (In this
case e.g. Dim intMyArr (5) As Integer would create the array structure with room for five
integers indexed 1 to 5) However it is advisable to explicitly declare the lower and upper
bounds with :
(lower To upper) so e.g. Dim intMyArr (0 To 4) As Integer shows the style we will use
from now on with the value for lower explicitly given and put at 0.
The syntax extends what you already have seen for simple variables.

Combo box control

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DescriptionA combo box combines the features of a text box and a list box. Use a combo box to give theuser the choice of either typing in the text box ( upper part) or selecting an item from the list(lower part) of the control. A combo box is preferable when you want to give the user a list ofsuggested options (but the user is free to enter own choice as well as list chioces). A list boxshould be used when you want to limit the users to a specific set of options. A combo box isotherwise identical (in terms of methods and properties) to a list box.

List Box and Combo Box

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List Box ControlDescriptionA list box displays a list of items from which the user can select one or more. If the number ofitems exceeds what can be displayed, a scroll bar is automatically added to the list box.If no item is selected, the ListIndex property value is -1. The first item in the list if selectedmakes the ListIndex become 0, the second item makes it 1 and so on and ListCount is alwaysone more than the largest ListIndex value.The most important properties of list boxes are List, Listcount and Listindex and the mostimportant methods are Additem and Removeitem.Remarks· To add or delete items in a list, use the AddItem or RemoveItem method.· Set the List, ListCount, and ListIndex properties to enable a user to access items in thelist.Additem methodAdds an item to a ListBox or ComboBox control or adds a row to a Grid control. Doesn'tsupport named arguments.

Dialog Boxes.

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Apart from the predefined dialog boxes MsgBox and InputBox there are other kinds whichgive the programmer more flexibility in controlling the dialogue interface. The other two kindsare:· Custom Dialog· Common DialogCustom DialogThis is a just another way to describe a VB form which has controls for input output etc. andobviously can have various properties set to facilitate easy and error controlled input. Usuallythe form is special purpose in that it is separate from the main (or higher level) form and usedpurely for some I/O related purpose ("screen based entry form"). Suppose a programDialogs.vbp has a main form called frmDialogs (which is kept in a file called dialogs.frm) andit includes customised menus – one of the menu items launches a custom dialog box calledfrmGetMonth

Where do People Use Wi-Fi?

2008-08-06T10:10:00.001+05:30

Sometimes people say that Wi-Fi is freedom. They can connect to Internet from their own home, office or a hotel room. It is possible without using any wires. Furthermore, wireless LAN is much faster than the modem connection. Of course our computer must be in range of the base station. Using different amplifiers we can easily change our location within a large area. Wireless LAN is a great solution of office networks. People can save on hardware and cables and it is also quite easy to move computers within the range of the base station (workers can take their laptops to conferences; when the range is big enough, they can sometimes use the computers at home). It can be used also in home business, in hotels, travel offices, shops, libraries, schools, etc. WLAN is can also be used as a home network, when we have a computer in an office room, in the kitchen and in a children's room. We would be able to look for cooking recipe in the net without leaving the kitchen. It would be possible for our children to use their own computer for preparing school projects while sitting in their room. We could share files, printers and even play multiplayer games, and that would save some money on hard disks or peripherals. Wireless LANs do not cause trouble to administrators because they are as simple in management as the wired networks. At the same time we eliminate the possibility of destroying the wires. The installation and scaling are very simple.

Security WIFI

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What about the security? Is there a possibility of stealing our data? Security is your personal decision, but having a wireless connection we should pay attention to protect our private files and encrypt sent messages. Actually, the security modules were very important since the beginning of the Wi-Fi projection. In order to prevent intercepting your data by the others the designers implemented many security techniques, like Wi-Fi Protected Access (based on encryption), Virtual Private Network (making virtual "tunnels"), Media Access Control Filtering (rejecting unknown MAC addresses), RADIUS Authentication and Authorization (using login and password) or Kerberos (key distribution). There is also a possibility to combine some of these security mechanisms making your transmissions even more secure.On the other hand providing such security in public places (like Internet cafes) may not meet its expectations. Connecting to protected wireless network you will be asked about a security code, encryption key or a password. If you do not know them, you will not be able to establish a communication link and use Internet resources. Most of public areas do not use security modules because of that reason making Wi-Fi users data unsafe.

Wi-Fi is a multi-purpose way of networking. People can apply it almost everywhere - in a house, office etc. It is also very flexible. Computers can be easily moved within its range. The users avoid different problems, such as destroying the wires. Wireless networking is a very cheap technology. We do not have to employ an administrator because the use is very simple. It is easy to use the Internet, check e-mail from each computer we have in our local network. Resources sharing is as easy as never before. People do not have to spend money on printers or hard disks. For example, it is possible to buy one big disk instead of a few smaller ones. That saves money. Using wireless LANs in offices is very advantageous. Programmers can easily co-operate while working on a complicated program, they are allowed to take their portable computers to conferences and to use the Internet's resources then. Briefly put, future belongs to Wi-Fi. This technology is still developing and already now is on a high level. It becomes more and more common for people. It's certain that within a few years wireless LANs will replace the wired ones.

Why / Where Should We Use Wi-Fi

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The Wi-Fi LAN has a broad application nowadays. Because of the comfortable and quick installation people often replace old wired LANs with Wi-Fi. Such connection allows to move your machine around the place without losing the Internet or other network resources. Working on your laptop you can check your mail from anywhere in your home or office. Some highly attended places like airports, libraries, schools or even coffee bars offer you constant Internet connection using exactly wireless LAN, so retrieving new files, cruising the global network or corresponding with others will not be a problem anymore in those (and many other) places.The most important shortcoming in Wi-Fi is the range. So far we may have difficulties in making a connection with a receiver which is more than 50-75 meters away (inside the buildings). The signal should be stronger to provide larger connectable spaces. Additionally, some of the wireless adapters works on the frequencies that are currently used by many other wireless devices. It can cause a serious interference, so the connection performance can be quite poor.However, building Wi-Fi network is often the cheapest way to achieve the desired connection with the surroundings. The price of a single wireless adapter is decreasing almost every day, so making a large network area by means of Wi-Fi is the most reasonable way. You will not need to arrange all the wires around and profit by the installation time. By the way, most of the Wi-Fi adapters have user-friendly configuration and diagnostic tools which can help you to adjust or change your WLAN settings or even can do everything for you.

History of Wi-Fi

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The first wireless LANs came into being in 1994. Then Wi-Fi cards were so expensive (about five times more than now) and this blocked its development. In 1997 the Institute of Electrical and Electronic Engineers worked out the 802.11 standard. However people forgot about it very soon because of low capacity. Only in 1999 they introduced the 802.11b standard which brought higher capacities. This standard's development was a milestone because the biggest world-famous producers became interested in this technology. For example Cisco Systems or 3COM. The next step in the evolution of Wi-Fi was the 802.11a standard creation. The 802.11a ought to be theoretically faster. Nevertheless it did not gain support because of high hardware's prices, incompatibility with the 802.11b standard and smaller range than the latter. In 2002, at trade fair "Comdex 2002", there were presented some devices which could work in the new 802.11g standard. In 2003 this standard gained approval of IEEE and appeared in most producers' offers. 802.11g joins the capacity which is comparable to "a" and has the range like the "b" one. On the other hand, the signal might be interfered by mobile phones, microwave ovens and sometimes the Bluetooth.

WLAN Definition

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WLAN - Wireless Local Area Network is a networking technology that allows the user to connect his computer to other ones without any wires. It is called "local" because of its rather small range. On the American market the success is being achieved by Wi-Fi and Wi-Fi5 - these are new-generation wireless networks. The name Wi-Fi, which is an abbreviation of Wireless Fidelity, was created by international organization called Wi-Fi Alliance. The main purpose of its members is examining the compatibility, certifying and promoting hardware designed for Wi-Fi net. Thanks to Wi-Fi Alliance networks built in this way compete with popular Bluetooth technology.Wi-Fi is related to 802.11 standard, which was designed by the Institute of Electrical and Electronic Engineers, and makes basis of WLANs building. According to the standard, wireless communication takes place in Spread Spectrum (SS). It means that the sent signal is distracted to frequency band wider than required for sending information. The 802.11 standard defines several ways of communication between the transmitter and the receiver (these are called modulations): DSSS - Direct Sequence Spread Spectrum FHSS - Frequency Hoping Spread Spectrum IR - Infrared OFDM - Orthogonal Frequency Division Multiplexing.

How GNSS Works

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A GNSS uses satellite positioning techniques to provide users with accurate and timely navigation information. A global positioning system is a subset of a global navigation satellite system because a GPS system need only provide the ability to determine position information. A GNSS must include:
Real time navigation information
It must be possible to generate real-time navigation information fast enough for safe navigation. The TRANSIT satellite system required several satellite passes to determine a position. Because an aircraft can't sit still for several hours, TRANSIT was not sufficient for aircraft navigation. Both the NAVSTAR and GLONASS systems provide near-instantaneous position (close enough.)
Autonomous integrity checking
There must be some way for the user to determine the accuracy of the navigation solution in a timely fashion. It would be bad for an airplane to hit the ground in front of a runway because a GPS satellite is transmitting bad information. Generally this problem is solved by having the aircraft view a large enough number of satellites that it can calculate several sets of redundant positions, comparing them against each other. Bad solutions can be detected and thrown out. At this time, neither the NAVSTAR or GLONASS systems have enough satellites to do this. The only way to do it is to use both NAVSTAR and GLONASS satellites at the same time.
Accuracy sufficient for safe navigation.
The U.S. Department of Transportation has determined that the most stringent requirements for aircraft landing are 4.1 meters horizontal accuracy and 0.6 meters vertical accuracy. There is no way for either NAVSTAR or GLONASS to provide this accuracy without external aids. Therefore, a GNSS using NAVSTAR and GLONASS must include these aids.

What is GNSS?

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GNSS stands for Global Navigation Satellite System. There are currently no GNSS systems in operation; however, several are planned. These systems will use either or both NAVSTAR and GLONASS to provide positioning, along with other components to improve accuracy and provide fast warning of problems.

How GPS Works - The Short Explanation

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A global positioning system uses the characteristics of radio transmissions for location determination. Unlike previous navigation systems using ground based transmitters, satellite based transmitters are used to cover earth with higher accuracy that that available from the land based systems. The satellites transmit timing information, satellite location information and satellite health information. The Space Segment is technical term for the satellites that belong to the system.
The user requires a special radio receiver - a GPS receiver - to receive the transmissions from the satellite. The GPS receiver contains a specialized computer that calculates the location based on the satellite signals. The user does not have to transmit anything to the satellite and the satellite does not know the user is there. There is no limit to the number of users that can be using the system at any one time. The users with their receivers are known as the User Segment.
The satellites are controlled and monitored from ground stations (the Control Segment). The control stations monitor the satellites for health and accuracy. Maintenance commands, orbital parameters and timing corrections are uploaded from the ground on a periodic basis.
Both NAVSTAR and GLONASS provide two sets of positioning signals. The higher accuracy system is reserved for each country's military use. The lower accuracy system is freely available to civilian users.

What Is GPS?

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GPS stands for Global Positioning System. Users of a global positioning system can calculate their location anywhere on the earth. There are currently two "public" GPS systems. The NAVSTAR system is owned by the United States and is managed by the Department of Defense. The GLONASS system is owned by the Russian Federation. While both NAVSTAR and GLONASS systems are global positioning systems, the NAVSTAR system is often referred to (in the U.S., anyway) as the GPS because it was generally available first. Nevertheless, both systems are GPS systems and the reader should keep this in mind.
The NAVSTAR system is managed by the NAVSTAR GPS Joint Program Office, located at Los Angeles Air Force Base. The civilian point of contact for NAVSTAR information is the U.S. Coast Guard's Navigation Center (NAVCEN). The NAVCEN provides system status information in the form of a document called a Notice Advisory to Navstar Users (NANU). Civil users have input to NAVSTAR system issues through the Civil GPS Service Interface Committee (CGSIC), which is organized by the Coast Guard.
The point of contact for GLONASS information is the Russian Space Forces' Coordinational Scientific Information Center (CSIC). The CSIC presents system status information in the form of a document called a Notice Advisory to Glonass Users (NAGU).

Automatic Vehicle Location (AVL)

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Automatic Vehicle Location (AVL) is a technologically advanced method of remote vehicle tracking and monitoring using GPS. Each vehicle is equipped with a module that receives signals from a series of satellites, and calculates its current geographical location, speed, and heading. This information can be stored for later retrieval or, frequently, transmitted to a central dispatch/control location where it is displayed on a high-resolution geographical map.

Global Positioning Systems (GPS) are space-based radio positioning systems that provide 24 hour three-dimensional position, velocity and time information to suitably equipped users anywhere on or near the surface of the Earth (and sometimes off the earth). Global Navigation Satellite Systems (GNSS) are extended GPS systems, providing users with sufficient accuracy and integrity information to be useable for critical navigation applications. The NAVSTAR system, operated by the U.S. Department of Defense, is the first GPS system widely available to civilian users. The Russian GPS system, GLONASS, is similar in operation and may prove complimentary to the NAVSTAR system.
These systems promise radical improvements to many systems that impact all people. By combining GPS with current and future computer mapping techniques, we will be better able to identify and manage our natural resources. Intelligent vehicle location and navigation systems will let us avoid congested freeways and find more efficient routes to our destinations, saving millions of dollars in gasoline and tons of air pollution. Travel abord ships and aircraft will be safer in all weather conditions. Businesses with large amounts of outside plant (railroads, utilities) will be able to manage their resources more efficiently, reducing consumer costs.
However, before all these changes can take place, people have to know what GPS can do. This page is about practical GPS applications and where to find equipment and information. Hopefully, as a result of reading this page, you will be coming up with your own applications that make the most of our tax dollars already spent.

GPS Applications

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One of the fast-growing GPS applications is vehicle tracking. GPS-equipped fleet vehicles, public transportation systems, delivery trucks, and courier services use receivers to monitor their locations at all times. Public safety services, police, fire, and emergency medical services, are using GPS receivers to determine the nearest service vehicle to an emergency, enabling the quickest response in critical situations. Recently automobile manufacturers are installing moving-map displays guided by GPS receivers. For example, several Florida rental car companies are demonstrating GPS-equipped vehicles that give directions to drivers on display screens and through synthesized voice instructions.
*Triangulation: Collecting of signals from three or more satellites in carefully monitored orbit from which the receiver computes its own spatial relationship to each satellite to determine its position.

GPS Applications

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Global Position System (GPS) comprises of three parts

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24 satellites that orbit the Earth
Ground control stations which monitor the satellites
GPS receivers can be attached to persons or animals, or mounted on object, such as a vehicle The satellites are synchronized to emit encoded navigational information (exact positioning and exact time). Any vehicle equipped with a GPS receiver will intercept these transmissions. Using a simple mathematical formula derived from triangulation,* the receiver is able to calculate its own longitude, latitude, velocity and even altitude. For companies implementing GPS applications, this information, most often, would be transmitted to a central dispatch or control location.

Basic Concept of GPS-based Applications

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Fundamental concept in GPS applications is that you can determine fairly accurately (ordinarily within 10-30 meters) the location of any device that has a GPS transceiver mounted inside the device. This determination of this location is facilitated by a series of satellites maintained by US defense establishment. Having determined the location of an object one can track its movement as it moves. Therefore, you can implement a number of business and personal applications based on this location like fleet management, health services in the public sector and number delivery services.

What is Bluetooth?

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: Bluetooth is the name for a short-range radio frequency (RF) technology that operates at 2.4 GHz and is capable of transmitting voice and data. The effective range of Bluetooth devices is 32 feet (10 meters). Bluetooth transfers data at the rate of 1 Mbps, which is from three to eight times the average speed of parallel and serial ports, respectively.

IrDA vs Bluetooth

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If you examine the benefits of each technology, you can see that Bluetooth and IrDA are both critical to the marketplace. Each technology has advantages and drawbacks and neither can meet all users' needs. Bluetooth's ability to penetrate solid objects and its capability for maximum mobility within the piconet allows for data exchange applications that are very difficult or impossible with IrDA. For example, with Bluetooth a person could synchronize their phone with a PC without taking the phone out of their pocket or purse (this is not possible with IrDA). The omni-directional capability of Bluetooth allows synchronization to start when the phone is brought into range of the PC.The Bluetooth standard defines the layers 1 and 2 of the OSI model. The application framework of Bluetooth is aimed to achieve interoperability with IrDA and WAP. In addition, a host of other applications will be able to use the Bluetooth technology and protocols.

IrDA

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IrDA is an international organization that creates and promotes interoperable, low-cost infrared data interconnection standards. IrDA has a set of protocols covering all layers of data transfer and in addition has some network management and interoperability designs. IrDA protocols have IrDA DATA as the vehicle for data delivery and IrDA CONTROL for sending the control information. [Feng99] [Williams00] IrDA DATA defines a standard for an interoperable universal two way cordless infrared light transmission data port. Adapters now include the traditional upgrades to serial and parallel ports
Features:
Range: From contact to at least 1metre. Can be extended to 2 meters. A low power version relaxes the range objective for operation from contact through at least 20 cm between low power devices and 30 cm between low power and standard power devices. This implementation affords 10 times less power consumption. These parameters are termed the required maximum ranges by certain classes of IrDA featured devices and sets the end user expectation for discovery, recognition and performance.
Bi-directional communication is the basis of all specifications
Data transmission from 9600 b/s with primary speed/cost steps of 115 kb/s and maximum speed up to 4 Mb/s
Data packets are protected using a CRC (CRC-16 for speeds up to 1.152Mb/s and CRC-32 at 4 Mb/s).

MobileInfo's Advisory and Comments:

2008-08-06T09:59:00.001+05:30

There is significant hype about Bluetooth. It is not unlike WAP. The PR machinery of Bluetooth community, vendors and developers would make you believe that Bluetooth is going to solve all the problems of short-distance connectivity without wires at a low cost and in the near future. They may also not acknowledge any overlap with 802.11 wireless LAN or HomeRF technologies. Reality is a little bit different than the glossy Powerpoint presentations and speeches by eloquent VPs of marketing for these vendors. We advise the user organizations to apply a bit of caution to some of these claims. Here is our assessment:
· With the momentum going at this speed and R&D dollars committed, we should expect during 2001 a reasonable set of products at silicon level, chip level and device adapter level that the systems integrators can utilize in the finished products for enduser devices - from smart phones to laptops.
· The prices of Bluetooth-enabled components will remain high during first part of 2001and this will delay widespread adoption. By December, the prices had come down both as a result of ramp of production but also due to single chip implementations and general downturn in the economy.
· Increased competition and production will bring the prices down in 2002.
· Distance limitation of Bluetooth in the first version will limit its use to close-range applications only. From systems engineering perspective, we do not see much conflict with wireless LAN applications and Bluetooth. The former is well-tested technology spanning much longer distances and higher speed. Let us not get into fruitless arguments and use appropriate technology where its core applications are. Also, expect 802.11 wireless LAN adapters to decrease in prices.
· Bluetooth will inevitably go through a phase where real experience will fall short of the promise it held.
· The number of 1000 plus vendors will shrink to, may be, 100 plus who will survive the rationalization that will follow in 2002-2003 time frame. Therefore, stay with vendors who have holding power or those who have great alliances. Otherwise you will have to say goodbye to your initial Bluetooth experimentation. Security standards for Bluetooth are still in a formative stage. Which devices talks to which and how do users allow or deny access to other Bluetooth devices as they approach them is still not clear - it is still being discussed at SIG level in 802.15 subgroup of IEEE. Therefore, there is still a gap between the cup that holds Bluetooth Elixir and the lip that must sip it to reach short-distance connectivity salvation.

MobileInfo's Advisory and Comments:

2008-08-06T09:59:00.000+05:30

Some Bluetooth enabled products in the market

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Ericsson R520 Bluetooth/WAP/GPRS/Triband
Ericsson T36 Bluetooth/WAP/HSCSD/Triband
Alcatel OneTouch 700 GPRS, WAP, Bluetooth
TDK Bluetooth Product Range
Bluetooth-enabled Nokia 9110 linked to a FujiFilm digital camera
Ericsson Bluetooth GSM Headset
Ericsson Communicator

Bluetooth The Current State of the Technology (circa mid 2000)

2008-08-06T09:52:00.000+05:30

Bluetooth technology has moved fast in terms of standards adoption, early release of chip sets and a few demo products. Nonetheless, Bluetooth is in early stages of development from the point of view of its adoption in enduser applications.
To be more specific, Bluetooth technology is in a period where first release of specifications have been developed and adopted by the core members. Chips sets have been developed by several vendors and have been released to systems integrators. Software development kits have also been released by major vendors. A number of developers conferences have been held in Europe and North America. Now, the second level of developers like 3COM and extended Systems have got into the act to develop systems development tools that business application developers can use.

What are the Applications?

2008-08-06T09:50:00.000+05:30

Bluetooth has a tremendous potential in moving and synchronizing information in a localized setting. Potential for Bluetooth applications is huge, because we transact business and communicate more with people who are close by than with those who are far away - a natural phenomenon of human interaction. The following list represents only a small set of potential applications - in future many more imaginative applications will come along:
By installing a Bluetooth network in your office you can do away with the complex and tedious task of networking between the computing devices, yet have the power of connected devices. No longer would you be bound to fixed locations where you can connect to the network. Each Bluetooth device could be connected to 200 other devices making the connection of every device with every other possible. Since it supports both point to point and point to multipoint it will virtually make the maximum number of simultaneously linked devices unlimited.
The Bluetooth technology connects all your office peripherals wirelessly. Connect your PC or notebook to printers, scanners and faxes without the ugly and trouble some cable attachments. You can increase your freedom by connecting your mouse or the keyboard wirelessly to your computer.
If your digital cameras in Bluetooth enabled, you can send still or video images from any location to any location without the hassle of connecting your camera to the mobile phone on the wireline phone.

Modes of operation of bluetooth

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An interesting aspect of the technology is the instant formation of networks once the bluetooth devices come in range to each other. A piconet is a collection of devices connected via Bluetooth technology in an ad hoc fashion. A Piconet can be a simple connection between two devices or more than two devices. Multiple independent and non-synchronized piconets can form a scatternet. Any of the devices in a piconet can also be a member of another by means of time multiplexing. i.e a device can be a part of more than one piconet by suitably sharing the time. The Bluetooth system supports both point-to-point and point-to-multi-point connections. When a device is connected to another device it is a point to point connection. If it is connected to more that one (upto 7 ) it is a point to multipoint connection. Several piconets can be established and linked together ad hoc, where each piconet is identified by a different frequency hopping sequence. All users participating on the same piconet are synchronized to this hopping sequence. If a device is connected to more than one piconet it communicates in each piconet using a different hopping sequence. A piconet starts with two connected devices, such as a portable PC and cellular phone, and may grow to eight connected devices. All Bluetooth devices are peer units and have identical implementations. However, when establishing a piconet, one unit will act as a master and the other(s) as slave(s) for the duration of the piconet connection. In a piconet there is a master unit whose clock and hopping sequence are used to synchronize all other devices in the piconet. All the other devices in a piconet that are not the master are slave units. A 3-bit MAC address is used to distinguish between units participating in the piconet. Devices synchronized to a piconet can enter power-saving modes called Sniff and hold mode, in which device activity is lowered. Also there can be parked units which are synchronized but do not have a MAC addresses. These parked units have a 8 bit address, therefore there can be a maximum of 256 parked devices.

How Bluetooth Technology Works

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"Connective convenience"
Bluetooth is a high-speed, low-power microwave wireless link technology, designed to connect phones, laptops, PDAs and other portable equipment together with little or no work by the user. Unlike infra-red, Bluetooth does not require line-of-sight positioning of connected units. The technology uses modifications of existing wireless LAN techniques but is most notable for its small size and low cost. The current prototype circuits are contained on a circuit board 0.9cm square, with a much smaller single chip version in development. The cost of the device is expected to fall very fast, from $20 initially to $5 in a year or two. It is envisioned that Bluetooth will be included within equipment rather than being an optional extra. When one Bluetooth product comes within range of another, (this can be set to between 10cm and 100m) they automatically exchange address and capability details. They can then establish a 1 megabit/s link (up to 2 Mbps in the second generation of the technology) with security and error correction, to use as required. The protocols will handle both voice and data, with a very flexible network topography.This technology achieves its goal by embedding tiny, inexpensive, short-range transceivers into the electronic devices that are available today. The radio operates on the globally-available unlicensed radio band, 2.45 GHz (meaning there will be no hindrance for international travelers using Bluetooth-enabled equipment.), and supports data speeds of up to 721 Kbps, as well as three voice channels. The bluetooth modules can be either built into electronic devices or used as an adaptor. For instance in a PC they can be built in as a PC card or externally attached via the

Blue tooth

2008-08-06T09:46:00.001+05:30

"Think of a connected world of electronic devices and appliances around you! You click on an icon for a device and you are linked to it, automatically and transparently"
Bluetooth technology eliminates the need for numerous and inconvenient cable attachments for connecting fixed computers, mobile phones, mobile computers, handheld devices, digital cameras and even new breed of digital appliances. It will enable users to connect a wide range of computing and telecommunications devices easily and simply, without the need to buy, carry, or connect cables - quite often proprietary to a specific device. It delivers opportunities for rapid ad hoc connections, and the possibility of automatic, unconscious, connections between devices. It creates the possibility of using mobile data in a variety of applications.
Bluetooth makes wireless communication and networking between devices in a small localized area of a room or a small office as easy as switching on the light. In Bluetooth all the connections between devices are instantaneous and invisible and the devices can talk even if they are not in line of sight because Bluetooth utilizes a radio-based link. Your laptop could send information to a printer in the next room, or your microwave could send a message to your mobile phone telling you that your meal is ready.
Bluetooth is actually a standard for wireless communications between devices in a personal area network (PAN) using radio frequency for a short range (around 10 meters). So any two devices that follow the standard can communicate and exchange data between each other without the need of any connection to be made between them. A group of Bluetooth devices like a mobile phone, a digital camera, a hand held device etc. can instantly form a network with each other as soon as they are switched on. You could have a mobile phone in your pocket and you could be sending e-mails using your laptop without making any connection between your laptop and the mobile. Your refrigerator could be placing an order with the supermarket if your milk supply has been exhausted using your mobile phone.
Briefly, Bluetooth technology
uses radio waves in 2.4 GHz band - therefore, no line of sight is required
supports multipoint, not just point to point
works in a small confined area - 10 to 15 meters apart
is able to support speeds of 1-2 Mbps today but will offer higher speeds in future
chip sets are relatively inexpensive (though more expensive than IrDA)- $10 to $20 today in large quantities - will go down in future
has significant industry support with over 1800 members in the industry

Hover Button Control

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Hover Button is button control exactly like the default CommandButton Control, Except he can change his Picture, And/Or his BackColor And/Or his Caption when the user is moving the mouse cursor over him, And when the user press the button (similar to the Internet Explorer buttons).

The process is very simple. Enter into the HoverPicture Property the picture that the button will display when the user hover above him. Do the same with the HoverCaption Property and the HoverBackColor Property.
Enter into the DownPicture Property the picture that the button will display when the user press the button. Do the same with the DownCaption Property and the DownBackColor Property.
This control is freeware.

Explain Relational operators.Explain Relational operators.

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A relational operator is a mathematical symbol that indicates a certain type of comparison between two values.
The equalities between number can be described as 2+2=4 and between character such as city=’London’.
Suppose you want to see all the salespeople with commission above certain amount, then you would use greater than type of comparison between two values.
The following relational operators are used in oracle:

= Equal to
> Greater than
< Less than
>= Greater than or equal to
<= Less than or equal to
<> Not equal to

These operators have the standard meanings for numeric values.
For character values their definition depends on the conversion format, ASCII or EBCDIC.
Even character values such as ‘1’ which represent numbers do not necessarily equal the number they represent.
You can use relational operators to represent alphabetical order. Ex: ‘a’<’n’ means a precedes n in alphabetical order.
In both ASCII and EBCDIC characters are less than all other characters that they precede in alphabetical order.
In ASCII, all uppercase characters are less than all lowercase characters, so that ‘Z’ < ‘a’ and all numbers are less than all characters, so that ‘1’< ‘Z’.
Both of these are reversed in EBCDIC.

ALTER COMMAND

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The structure of table can be modified using ALTER COMMAND.
It is used to add or delete column in the table.
It is also used to modify already existing column of a table to either change its data-type or to increase or decrease its width/size of the column.
It is also used rename the columns of the table.

Following restrictions should be taken care of while ALTER COMMAND:
Change the name of the table
Change the name of the columnDecrease the size of a column if table data exists.

INSERT COMMAND

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It is used to insert records in the table which is created.
Char and date data-type columns should be enclosed in single quotes while inserting records in the table.
Number data-type column should be written without single quotes.

Records can be inserted into the table in three ways:

Rules for creating tables

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A name can have maximum up to 30 characters.
Alphabets from A-Z, a-z and numbers from 0-9 are allowed.
A name should begin with alphabet.
The use of special character like _ is allowed and also recommended.
SQL reserved words are not allowed. Ex : select, create and so on.

Create command

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It is used to create table in database.
Each column can have minimum three attributes name, data type and size (width).
Each column name is separated by comma operator.
The column can have mainly three data type (number, char, date).
The size or width specify to column name gives the details about how much data can be inserted in specific column.Each lines ends with semicolon.

Queries Of Relational And Logical Operator.

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1) List the name of salesman whose name is of 3 character and second letter is ‘a’.
2) List all the record of salesman whose address is start with ‘a’.
3) List the entire salesman whose pin is grater than 400030.
4) List all the clients whose city’s second letter is ‘a’.
5) List all the clients whose client_no is grater than c00003 and baldue is equal to 0.
6) List name,city,baldue of client whose city start with ‘m’ and baldue is 0.
7) List all the client whose city is Mumbai or state Karnataka.
8) List the product where quantity on hand is grater than 100 and reorderlevel is 50.
9) List all record of product where reorder level is 50 and cost price is grater than 500.
10) List the record of the product where sell price is greater than 500 or cost price is less than 500.
11) List the products where description starts with ‘s’.
12) List all the products whose quantity on hand is between 100 and 200.
13) List all the product where quantity on hand in 200,150,100.
14) List name, city of client where city in Mumbai, Madras.
15) List the product where profit percent between 5 and 10.
16) List the record of the client whose city is not Mumbai.
17) List the record of the client whose city is not Mumbai and state is not Karnataka.
18) List all the record of salesman whose ytdsales is not in 50,100.
19) List all the product whose second character is ‘e’.
20) List all the clients where second character of state is ‘a’.

To retrive the information from the table: -

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1) Display the complete list of salespeople table.
2) Display salesperson’s name, city and comm fields.
3) Display odate ,snum , and onum of orders table.
4) Display unique(not allow duplicate)snum from orders table.
5) Display all columns of salespeople whose city is London.
6) Display name, city columns of salespeople whose city is London.
7) Display all columns of customer whose rating is equal to 100.
8) Display all rows from customer table for which salesperson’s number is 1001.
9) Display city, sname, snum, and comm in mentioned order.
10) Write the select command that produces the rating followed by the name of each customer in San Jose.

The SIGNAL procedure

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The SIGNAL procedure

The SIGNAL procedure signals that an alert has been fired and passes a message to all sessions currentlyhaving registered interest in the alert. The specification is:

PROCEDURE DBMS_ALERT.SIGNAL (name IN VARCHAR2, message IN VARCHAR2);

The SET_DEFAULTS procedure

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The SET_DEFAULTS procedure

Use the SET_DEFAULTS procedure to set the amount of time (in seconds) for the POLLING_INTERVAL,which applies when DBMS_ALERT goes into a polling loop. The specification is:

PROCEDURE DBMS_ALERT.SET_DEFAULTS (sensitivity IN NUMBER);

The REMOVEALL procedure

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The REMOVEALL procedure

The REMOVEALL procedure removes all alerts for the current session from the registration list. After a callto REMOVEALL, your application will no longer respond to any alerts issued by SIGNAL. The specificationis:

PROCEDURE DBMS_ALERT.REMOVEALL;

The REMOVE procedure

2008-07-30T09:40:00.000+05:30

The REMOVE procedure

The REMOVE procedure removes the specified alert for the current session from the registration list. After acall to REMOVE, your application will no longer respond to the named alert when issued by SIGNAL. Thespecification is:

PROCEDURE DBMS_ALERT.REMOVE (name IN VARCHAR2);

The REGISTER procedure

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The REGISTER procedureThe REGISTER procedure adds your session and the specified alert to the master registration list. A sessioncan register its interest in any number of alerts. The specification is:

PROCEDURE DBMS_ALERT.REGISTER (name IN VARCHAR2);

No Direct Remote Procedure Calls

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This very powerful feature is unavailable from Oracle Developer/2000. Instead, you will have to create asynonym for the remote procedure and then execute the synonym rather than the procedure directly. (Don'tforget to grant EXECUTE authority on the synonym!)

Scanner

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A device used to copy an image from a physical source (e.g., a photograph) into a computer. A device that takes a picture of an image breaks it down into dots and records it as a digital file for use with a computer. A device that reads a printed page and converts it into a graphics image for the computer A device that can electronically read text or pictures and save them in a format where they can be used in other packages such as Word.

What You Have Learnt

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In this lesson systematic approach of any given problem is explained. Computer based systems are defined. System development life cycle is discussed in detail. The different phases of the development of system life cycle are explained in detail.

Terminal Question
Define a system. Explain the components of a system.
What do you understand by system development life cycle? Discuss the importance of system analysis and design in the development of a system?

PHASES OF SYSTEM DEVELOPMENT LIFE CYCLE

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Let us now describe the different phases and the related activities of system development life cycle in detail.
(a) System Study
System study is the first stage of system development life cycle. This gives a clear picture of what actually the physical system is? In practice, the system study is done in two phases. In the first phase, the preliminary survey of the system is done which helps in identifying the scope of the system. The second phase of the system study is more detailed and in-depth study in which the identification of user’s requirement and the limitations and problems of the present system are studied. After completing the system study, a system proposal is prepared by the System Analyst (who studies the system) and placed before the user. The proposed system contains the findings of the present system and recommendations to overcome the limitations and problems of the present system in the light of the user’s requirements.
To describe the system study phase more analytically, we would say that system study phase passes through the following steps:
problem identification and project initiation
background analysis
inference or findings
(b) Feasibility Study
On the basis of result of the initial study, feasibility study takes place. The feasibility study is basically the test of the proposed system in the light of its workability, meeting user’s requirements, effective use of resources and .of course, the cost effectiveness. The main goal of feasibility study is not to solve the problem but to achieve the scope. In the process of feasibility study, the cost and benefits are estimated with greater accuracy.
(c) System Analysis
Assuming that a new system is to be developed, the next phase is system analysis. Analysis involved a detailed study of the current system, leading to specifications of a new system. Analysis is a detailed study of various operations performed by a system and their relationships within and outside the system. During analysis, data are collected on the available files, decision points and transactions handled by the present system. Interviews, on-site observation and questionnaire are the tools used for system analysis. Using the following steps it becomes easy to draw the exact boundary of the new system under consideration:
Keeping in view the problems and new requirements
Workout the pros and cons including new areas of the system
All procedures, requirements must be analysed and documented in the form of detailed data flow diagrams (DFDs), data dictionary, logical data structures and miniature specifications. System Analysis also includes sub-dividing of complex process involving the entire system, identification of data store and manual processes.
The main points to be discussed in system analysis are:
Specification of what the new system is to accomplish based on the user requirements.
Functional hierarchy showing the functions to be performed by the new system and their relationship with each other.
Function network which are similar to function hierarchy but they highlight the those functions which are common to more than one procedure.
List of attributes of the entities - these are the data items which need to be held about each entity (record)
(d) System Design
Based on the user requirements and the detailed analysis of a new system, the new system must be designed. This is the phase of system designing. It is a most crucial phase in the development of a system. Normally, the design proceeds in two stages :
preliminary or general design
Structure or detailed design
Preliminary or general design: In the preliminary or general design, the features of the new system are specified. The costs of implementing these features and the benefits to be derived are estimated. If the project is still considered to be feasible, we move to the detailed design stage.
Structure or Detailed design: In the detailed design stage, computer oriented work begins in earnest. At this stage, the design of the system becomes more structured. Structure design is a blue print of a computer system solution to a given problem having the same components and inter-relationship among the same components as the original problem. Input, output and processing specifications are drawn up in detail. In the design stage, the programming language and the platform in which the new system will run are also decided.
There are several tools and techniques used for designing. These tools and techniques are:
Flowchart
Data flow diagram (DFDs)
Data dictionary
Structured English
Decision table
Decision tree
Each of the above tools for designing will be discussed in detailed in the next lesson.
(e) Coding
After designing the new system, the whole system is required to be converted into computer understanding language. Coding the new system into computer programming language does this. It is an important stage where the defined procedure are transformed into control specifications by the help of a computer language. This is also called the programming phase in which the programmer converts the program specifications into computer instructions, which we refer as programs. The programs coordinate the data movements and control the entire process in a system.
It is generally felt that the programs must be modular in nature. This helps in fast development, maintenance and future change, if required.
(f) Testing
Before actually implementing the new system into operations, a test run of the system is done removing all the bugs, if any. It is an important phase of a successful system. After codifying the whole programs of the system, a test plan should be developed and run on a given set of test data. The output of the test run should match the expected results.
Using the test data following test run are carried out:
Unit test
System test
Unit test: When the programs have been coded and compiled and brought to working conditions, they must be individually tested with the prepared test data. Any undesirable happening must be noted and debugged (error corrections).
System Test: After carrying out the unit test for each of the programs of the system and when errors are removed, then system test is done. At this stage the test is done on actual data. The complete system is executed on the actual data. At each stage of the execution, the results or output of the system is analysed. During the result analysis, it may be found that the outputs are not matching the expected out of the system. In such case, the errors in the particular programs are identified and are fixed and further tested for the expected output.
When it is ensured that the system is running error-free, the users are called with their own actual data so that the system could be shown running as per their requirements.
(g) Implementation
After having the user acceptance of the new system developed, the implementation phase begins. Implementation is the stage of a project during which theory is turned into practice. During this phase, all the programs of the system are loaded onto the user's computer. After loading the system, training of the users starts. Main topics of such type of training are:
How to execute the package
How to enter the data
How to process the data (processing details)
How to take out the reports
After the users are trained about the computerised system, manual working has to shift from manual to computerised working. The following two strategies are followed for running the system:
Parallel run: In such run for a certain defined period, both the systems i.e. computerised and manual are executed in parallel. This strategy is helpful because of the following:
Manual results can be compared with the results of the computerised system.
Failure of the computerised system at the early stage, does not affect the working of the organisation, because the manual system continues to work, as it used to do.
Pilot run: In this type of run, the new system is installed in parts. Some part of the new system is installed first and executed successfully for considerable time period. When the results are found satisfactory then only other parts are implemented. This strategy builds the confidence and the errors are traced easily.
(h) Maintenance
Maintenance is necessary to eliminate errors in the system during its working life and to tune the system to any variations in its working environment. It has been seen that there are always some errors found in the system that must be noted and corrected. It also means the review of the system from time to time. The review of the system is done for:
knowing the full capabilities of the system
knowing the required changes or the additional requirements
studying the performance If a major change to a system is needed, a new project may have to be set up to carry out the change. The new project will then proceed through all the above life cycle phases.

SYSTEM LIFE CYCLE

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System life cycle is an organisational process of developing and maintaining systems. It helps in establishing a system project plan, because it gives overall list of processes and sub-processes required developing a system.
System development life cycle means combination of various activities. In other words we can say that various activities put together are referred as system development life cycle. In the System Analysis and Design terminology, the system development life cycle means software development life cycle.

Following are the different phases of software development cycle:

System study
Feasibility study
System analysis
System design
Coding
Testing
Implementation
Maintenance

Defining A System

2008-07-23T09:38:00.000+05:30

A collection of components that work together to realize some objective forms a system. Basically there are three major components in every system, namely input, processing and output.

In a system the different components are connected with each other and they are interdependent. For example, Human body represents a complete natural system. We are also bound by many national systems such as political system, economic system, educational system and so forth. The objective of the system demand that some output is produced as a result of processing the suitable inputs.

Introduction to System Analysis and Design

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1 INTRODUCTION

Systems are created to solve problems. One can think of the systems approach as an organized way of dealing with a problem. In this dynamic world, The subject System Analysis and Design, mainly deals with the software development activities.

2 OBJECTIVES

After going through this lesson, you should be able to:
understand a system
understand the different phases of system developments life cycle
know the components of system analysis
know the components of system designing

Minimum Function

2008-07-16T18:34:00.002+05:30

min()
-- Find lowest value
Syntax : mixed min ( number arg1, number arg2 [, number ...])

Syntax : mixed min ( array numbers [, array ...])
min() returns the numerically lowest of the parameter values.
If the first and only parameter is an array, min() returns the lowest value in that array. If the first parameter is an integer, string or float, you need at least two parameters and min() returns the smallest of these values. You can compare an unlimited number of values.

Note: PHP will evaluate a non-numeric string as 0, but still return the string if it's seen as the numerically lowest value. If multiple arguments evaluate to 0, min() will use the first one it sees (the leftmost value).

Fmod Function

2008-07-16T18:34:00.001+05:30

max()
-- Find highest value

Syntax : mixed max ( number arg1, number arg2 [, number ...])mixed max ( array numbers [, array ...])
max() returns the numerically highest of the parameter values.
If the first and only parameter is an array, max() returns the highest value in that array. If the first parameter is an integer, string or float, you need at least two parameters and max() returns the biggest of these values. You can compare an unlimited number of values.
Note: PHP will evaluate a non-numeric string as 0, but still return the string if it's seen as the numerically highest value. If multiple arguments evaluate to 0, max() will use the first one it sees (the leftmost value).

Fmod function

2008-07-16T18:33:00.000+05:30

fmod()
Returns the floating point remainder (modulo) of the division of the arguments

Syntax : float fmod ( float x, float y)
Returns the floating point remainder of dividing the dividend (x) by the divisor (y). The reminder (r) is defined as: x = i * y + r, for some integer i. If y is non-zero, r has the same sign as x and a magnitude less than the magnitude of y.

Round Function

2008-07-16T18:32:00.002+05:30

round()
-- Rounds a float

Syntax : float round ( float val [, int precision])
Returns the rounded value of val to specified precision (number of digits after the decimal point). precision can also be negative or zero (default).

Floor Function

2008-07-16T18:32:00.001+05:30

floor()
-- Round fractions down

Syntax: float floor ( float value)

Returns the next lowest integer value by rounding down value if necessary. The return value of floor() is still of type float because the value range of float is usually bigger than that of integer.

Maths Function

2008-07-16T18:31:00.002+05:30

Math Function
abs()
- Absolute value
Syntax : number abs (mixed number)

Returns the absolute value of number. If the argument number is of type float, the return type is also float, otherwise it is integer (as float usually has a bigger value range than integer).

ceil()
- Round fractions up

String

2008-07-16T18:31:00.001+05:30

String Function
Chr()
Return a specific character

Syntax : string chr ( int ascii)
Returns a one-character string containing the character specified by ascii.

Variable Length argument Function

2008-07-16T18:30:00.000+05:30

Variable length Argument Function
func_num_args()

Returns the number of arguments passed to the function

Syntax : int func_num_args ( void )
Returns the number of arguments passed into the current user-defined function. func_num_args() will generate a warning if called from outside of a user-defined function.

func_get_arg()
-- Return an item from the argument list

Syntax : mixed func_get_arg ( int arg_num)

Returns the argument which is at the arg_num'th offset into a user-defined function's argument list. Function arguments are counted starting from zero. func_get_arg() will generate a warning if called from outside of a function definition.
If arg_num is greater than the number of arguments actually passed, a warning will be generated and func_get_arg() will return FALSE.

= 2) { echo "Second argument is: " . func_get_arg(1) . "
\n"; }} foo (1, 2, 3);?>

func_get_args()

-- Returns an array comprising a function's argument list

Syntax : array func_get_args ( void )
Returns an array in which each element is the corresponding member of the current user-defined function's argument list. func_get_args() will generate a warning if called from outside of a function definition

= 2) { echo "Second argument is: " . func_get_arg(1) . "
\n"; } $arg_list = func_get_args(); for ($i = 0; $i < $numargs; $i++) { echo "Argument $i is: " . $arg_list[$i] . "
\n"; }} foo(1, 2, 3);?>

Installation of PHP

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Installing PHP on Windows with Apache 1.3.x
There are two ways to set up PHP to work with Apache 1.3.x on Windows. One is to use the CGI binary (php.exe), the other is to use the Apache module DLL. In either case you need to stop the Apache server, and edit your httpd.conf to configure Apache to work with PHP.
It is worth noting here that now the SAPI module has been made more stable under Windows, we recommend it's use above the CGI binary, since it is more transparent and secure.
Although there can be a few variations of configuring PHP under Apache, these are simple enough to be used by the newcomer. Please consult the Apache Docs for further configuration directives.
If you unziped the PHP package to c:\php\ as described in the Manual Installation Steps section, you need to insert these lines to your Apache configuration file to set up the CGI binary:
· ScriptAlias /php/ "c:/php/"
· AddType application/x-httpd-php .php .phtml
· Action application/x-httpd-php "/php/php.exe"
Note that the second line in the list above can be found in the actual versions of httpd.conf, but it is commented out. Remember also to substitute the c:/php/ for your actual path to PHP.
If you would like to use PHP as a module in Apache, be sure to copy php4ts.dll to the windows/system (for Windows 9x/Me), winnt/system32 (for Windows NT/2000) or windows/system32 (for Windows XP) directory, overwriting any older file. Then you should add the following lines to your Apache httpd.conf file:
· Open httpd.conf with your favorite editor and locate the LoadModule directive and add the following line at the end of the list for PHP 4: LoadModule php4_module "c:/php/sapi/php4apache.dll" or the following for PHP 5: LoadModule php5_module "c:/php/sapi/php5apache.dll"
· You may find after using the Windows installer for Apache that you need to define the AddModule directive for mod_php4.c. This is especially important if the ClearModuleList directive is defined, which you will find by scrolling down a few lines. You will see a list of AddModule entries, add the following line at the end of the list: AddModule mod_php4.c For PHP 5, instead use AddModule mod_php5.c
· Search for a phrase similar to # AddType allows you to tweak mime.types. You will see some AddType entries, add the following line at the end of the list: AddType application/x-httpd-php .php. You can choose any extension you want to parse through PHP here. .php is simply the one we suggest. You can even include .html, and .php3 can be added for backwards compatibility.
After changing the configuration file, remember to restart the server, for example, NET STOP APACHE followed by NET START APACHE, if you run Apache as a Windows Service, or use your regular shortcuts.
There are two ways you can use the source code highlighting feature, however their ability to work depends on your installation. If you have configured Apache to use PHP as an SAPI module, then by adding the following line to your httpd.conf (at the same place you inserted AddType application/x-httpd-php .php, see above) you can use this feature: AddType application/x-httpd-php-source .phps.
If you chose to configure Apache to use PHP as a CGI binary, you will need to use the show_source() function. To do this simply create a PHP script file and add this code: . Substitute original_php_script.php with the name of the file you wish to show the source of.
Note: On Win-Apache all backslashes in a path statement such as "c:\directory\file.ext", must be converted to forward slashes, as "c:/directory/file.ext".

PHP configration

2008-07-16T18:29:00.001+05:30

PHP Configuration
PHP Configuration in IIS
To install PHP on an NT/2000/XP Server running IIS 4 or newer, follow these instructions. You have two options to set up PHP, using the CGI binary (php.exe) or with the ISAPI module.
In either case, you need to start the Microsoft Management Console (may appear as 'Internet Services Manager', either in your Windows NT 4.0 Option Pack branch or the Control Panel=>Administrative Tools under Windows 2000/XP). Then right click on your Web server node (this will most probably appear as 'Default Web Server'), and select 'Properties'.
If you want to use the CGI binary, do the following:
· Under 'Home Directory', 'Virtual Directory', or 'Directory', click on the 'Configuration' button, and then enter the App Mappings tab.
· Click Add, and in the Executable box, type: c:\php\php.exe (assuming that you have unziped PHP in c:\php\).
· In the Extension box, type the file name extension you want associated with PHP scripts. Leave 'Method exclusions' blank, and check the Script engine checkbox. You may also like to check the 'check that file exists' box - for a small performance penalty, IIS (or PWS) will check that the script file exists and sort out authentication before firing up php. This means that you will get sensible 404 style error messages instead of cgi errors complaining that PHP did not output any data.
You must start over from the previous step for each extension you want associated with PHP scripts. .php and .phtml are common, although .php3 may be required for legacy applications.
· Set up the appropriate security. (This is done in Internet Service Manager), and if your NT Server uses NTFS file system, add execute rights for I_USR_ to the directory that contains php.exe.
To use the ISAPI module, do the following:
· If you don't want to perform HTTP Authentication using PHP, you can (and should) skip this step. Under ISAPI Filters, add a new ISAPI filter. Use PHP as the filter name, and supply a path to the php4isapi.dll.
· Under 'Home Directory', click on the 'Configuration' button. Add a new entry to the Application Mappings. Use the path to the php4isapi.dll as the Executable, supply .php as the extension, leave Method exclusions blank, and check the Script engine checkbox.
· Stop IIS completely (NET STOP iisadmin)
· Start IIS again (NET START w3svc)

Working of PHP

2008-07-16T18:28:00.000+05:30

What can PHP do?
Anything. PHP is mainly focused on server-side scripting, so you can do anything any other CGI program can do, such as collect form data, generate dynamic page content, or send and receive cookies. But PHP can do much more.
There are three main fields where PHP scripts are used.
· Server-side scripting. This is the most traditional and main target field for PHP. You need three things to make this work. The PHP parser (CGI or server module), a web server and a web browser. You need to run the web server, with a connected PHP installation. You can access the PHP program output with a web browser, viewing the PHP page through the server.

· Command line scripting. You can make a PHP script to run it without any server or browser. You only need the PHP parser to use it this way. This type of usage is ideal for scripts regularly executed using cron (on *nix or Linux) or Task Scheduler (on Windows). These scripts can also be used for simple text processing tasks.

· Writing client-side GUI applications. PHP is probably not the very best language to write windowing applications, but if you know PHP very well, and would like to use some advanced PHP features in your client-side applications you can also use PHP-GTK to write such programs. You also have the ability to write cross-platform applications this way. PHP-GTK is an extension to PHP, not available in the main distribution.
PHP can be used on all major operating systems, including Linux, many Unix variants (including HP-UX, Solaris and OpenBSD), Microsoft Windows, Mac OS X, RISC OS, and probably others. PHP has also support for most of the web servers today. This includes Apache, Microsoft Internet Information Server, Personal Web Server, Netscape and iPlanet servers, Oreilly Website Pro server, Caudium, Xitami, OmniHTTPd, and many others. For the majority of the servers PHP has a module, for the others supporting the CGI standard, PHP can work as a CGI processor.
So with PHP, you have the freedom of choosing an operating system and a web server. Furthermore, you also have the choice of using procedural programming or object oriented programming, or a mixture of them. Although not every standard OOP feature is realized in the current version of PHP, many code libraries and large applications (including the PEAR library) are written only using OOP code.
With PHP you are not limited to output HTML. PHP's abilities includes outputting images, PDF files and even Flash movies (using libswf and Ming) generated on the fly. You can also output easily any text, such as XHTML and any other XML file. PHP can autogenerate these files, and save them in the file system, instead of printing it out, forming a server-side cache for your dynamic content.
One of the strongest and most significant feature in PHP is its support for a wide range of databases. Writing a database-enabled web page is incredibly simple. The following databases are currently supported:
Adabas D
Ingres
Oracle (OCI7 and OCI8)
dBase
InterBase
Ovrimos
Empress
FrontBase
PostgreSQL
FilePro (read-only)
mSQL
Solid
Hyperwave
Direct MS-SQL
Sybase
IBM DB2
MySQL
Velocis
Informix
ODBC
Unix dbm
We also have a DBX database abstraction extension allowing you to transparently use any database supported by that extension. Additionally PHP supports ODBC, the Open Database Connection standard, so you can connect to any other database supporting this world standard.
PHP also has support for talking to other services using protocols such as LDAP, IMAP, SNMP, NNTP, POP3, HTTP, COM (on Windows) and countless others. You can also open raw network sockets and interact using any other protocol. PHP has support for the WDDX complex data exchange between virtually all Web programming languages. Talking about interconnection, PHP has support for instantiation of Java objects and using them transparently as PHP objects. You can also use our CORBA extension to access remote objects.
PHP has extremely useful text processing features, from the POSIX Extended or Perl regular expressions to parsing XML documents. For parsing and accessing XML documents, we support the SAX and DOM standards. You can use our XSLT extension to transform XML documents.
While using PHP in the e-commerce field, you'll find the Cybercash payment, CyberMUT, VeriSign Payflow Pro and CCVS functions useful for your online payment programs.
At last but not least, we have many other interesting extensions, the mnoGoSearch search engine functions, the IRC Gateway functions, many compression utilities (gzip, bz2), calendar conversion, translation.

whai is PHP

2008-07-16T18:27:00.000+05:30

Introduction to PHP

PHP, which stands for "PHP: Hypertext Preprocessor" is a widely-used Open Source general-purpose scripting language that is especially suited for Web development and can be embedded into HTML. Its syntax draws upon C, Java, and Perl, and is easy to learn. The main goal of the language is to allow web developers to write dynamically generated webpages quickly, but you can do much more with PHP.

PHP

2008-07-16T18:25:00.000+05:30

What is the different between cookies and session in php

Cookies are stored in client machine and sessions are stored in server machines.

What is the different between print and echo?
Echo is a construct. It takes command only. It takes multiple parameters and faster than print. Whereas print is also construct and function but print does not take multiple parameters it will return true (1) or false (2) or some values.
Echo is just a statement and not a function and doesn’t return a value or it justs prints a value whereas print () is a function, which prints a value and also returns a values.

How can we submit a form without submit button?

With javascript
With header function of PHP. Header (“location: $ur;”)

IGNOO

2008-07-16T18:20:00.000+05:30

A student of BCA final semester submits his project proposal to SOCIS, IGNOU, New Delhi. In a month's time, he will recieve communication from SOCIS about its approval. In case it is disapproved,student will be informed about the reason for its disapproval. In case it is approved, the student will be communicated about the same . After the student receives approval letter, he can submit project report to SR&E, IGNOU, New Delhi which will inform the student about the schedule of project viva to the student in due course. Then, the student attends for project viva and waits for the Grade card from IGNOU which contains the result fo his/here Project work. Students are required to study this problem and suggest the appropriate mechanism, for computerizing the operation. The computerization should be in such a way that IGNOU can attend to the queries of the student regarding the reciept of project proposal/ Approval/Disapproval fo Project Proposal, Receipt of Project Report and Schedule fo Project

Indexing

2008-07-15T14:27:00.001+05:30

What is indexing and what are the different kinds of indexing?
Indexing is a technique for determining how quickly specific data can be found.
Types:
Ø Binary search style indexing
Ø B-Tree indexing
Ø Inverted list indexing
Ø Memory resident table
Ø Table indexing

All Keys

2008-07-15T14:26:00.001+05:30

What is Domain-Key Normal Form?
A relation is said to be in DKNF if all constraints and dependencies that should hold on the the constraint can be enforced by simply enforcing the domain constraint and key constraint on the relation.

What are partial, alternate,, artificial, compound and natural key?
Partial Key:
It is a set of attributes that can uniquely identify weak entities and that are related to same owner entity. It is sometime called as Discriminator.
Alternate Key:
All Candidate Keys excluding the Primary Key are known as Alternate Keys.
Artificial Key:
If no obvious key, either stand alone or compound is available, then the last resort is to simply create a key, by assigning a unique number to each record or occurrence. Then this is known as developing an artificial key.
Compound Key:
If no single data element uniquely identifies occurrences within a construct, then combining multiple elements to create a unique identifier for the construct is known as creating a compound key.
Natural Key:
When one of the data elements stored within a construct is utilized as the primary key, then it is called the natural key.

1,2,3,4,5 Normal Form

2008-07-15T14:25:00.000+05:30

What is 1 NF (Normal Form)?
The domain of attribute must include only atomic (simple, indivisible) values.

What is Fully Functional dependency?
It is based on concept of full functional dependency. A functional dependency X Y is full functional dependency if removal of any attribute A from X means that the dependency does not hold any more.

What is 2NF?
A relation schema R is in 2NF if it is in 1NF and every non-prime attribute A in R is fully functionally dependent on primary key.

What is 3NF?
A relation schema R is in 3NF if it is in 2NF and for every FD X A either of the following is true
X is a Super-key of R.
A is a prime attribute of R.
In other words, if every non prime attribute is non-transitively dependent on primary key.

What is BCNF (Boyce-Codd Normal Form)?
A relation schema R is in BCNF if it is in 3NF and satisfies an additional constraint that for every FD X A, X must be a candidate key.

What is 4NF?
A relation schema R is said to be in 4NF if for every Multivalued dependency X Y that holds over R, one of following is true
X is subset or equal to (or) XY = R.
X is a super key.

What is 5NF?
A Relation schema R is said to be 5NF if for every join dependency {R1, R2, ..., Rn} that holds R, one the following is true
Ri = R for some i.The join dependency is implied by the set of FD, over R in which the left side is key of R.

Function Dependency

2008-07-15T14:24:00.000+05:30

What is Functional Dependency?

A Functional dependency is denoted by X Y between two sets of attributes X and Y that are subsets of R specifies a constraint on the possible tuple that can form a relation state r of R. The constraint is for any two tuples t1 and t2 in r if t1[X] = t2[X] then they have t1[Y] = t2[Y]. This means the value of X component of a tuple uniquely determines the value of component Y.

Normalization

2008-07-15T14:23:00.002+05:30

What is Set-at-a-time or Set-oriented?
The High level or Non-procedural DML can specify and retrieve many records in a single DML statement. This retrieve of a record is said to be Set-at-a-time or Set-oriented.

What is Relational Algebra?
It is procedural query language. It consists of a set of operations that take one or two relations as input and produce a new relation.

What is Relational Calculus?
It is an applied predicate calculus specifically tailored for relational databases proposed by E.F. Codd. E.g. of languages based on it are DSL ALPHA, QUEL.

How does Tuple-oriented relational calculus differ from domain-oriented relational calculus
The tuple-oriented calculus uses a tuple variables i.e., variable whose only permitted values are tuples of that relation. E.g. QUEL
The domain-oriented calculus has domain variables i.e., variables that range over the underlying domains instead of over relation. E.g. ILL, DEDUCE.

What is normalization?
It is a process of analysing the given relation schemas based on their Functional Dependencies (FDs) and primary key to achieve the properties
Minimizing redundancyMinimizing insertion, deletion and update anomalies.

DDL Inteprenur

2008-07-15T14:23:00.001+05:30

What is Query evaluation engine?
It executes low-level instruction generated by compiler.

What is DDL Interpreter?
It interprets DDL statements and record them in tables containing metadata.

What is Record-at-a-time?The Low level or Procedural DML can specify and retrieve each record from a set of records. This retrieve of a record is said to be Record-at-a-time.

Data Storage

2008-07-15T14:22:00.002+05:30

What is Data Storage - Definition Language?
The storage structures and access methods used by database system are specified by a set of definition in a special type of DDL called data storage-definition language.

What is DML (Data Manipulation Language)?
This language that enable user to access or manipulate data as organised by appropriate data model.
Procedural DML or Low level: DML requires a user to specify what data are needed and how to get those data.
Non-Procedural DML or High level: DML requires a user to specify what data are needed without specifying how to get those data.

What is DML Compiler?
It translates DML statements in a query language into low-level instruction that the query evaluation engine can understand.

DDL VDL SDL

2008-07-15T14:22:00.001+05:30

What is Relationship type?
Relationship type defines a set of associations or a relationship set among a given set of entity types.

What is degree of Relationship type?
It is the number of entity type participating.

What is DDL (Data Definition Language)?
A data base schema is specifies by a set of definitions expressed by a special language called DDL.

What is VDL (View Definition Language)?
It specifies user views and their mappings to the conceptual schema.

What is SDL (Storage Definition Language)?
This language is to specify the internal schema. This language may specify the mapping between two schemas.

Attribure & Relation

2008-07-15T14:21:00.002+05:30

What is an attribute?
It is a particular property, which describes the entity.

What is a Relation Schema and a Relation?
A relation Schema denoted by R(A1, A2, …, An) is made up of the relation name R and the list of attributes Ai that it contains. A relation is defined as a set of tuples. Let r be the relation which contains set tuples (t1, t2, t3, ..., tn). Each tuple is an ordered list of n-values t=(v1,v2, ..., vn).

What is degree of a Relation?
It is the number of attribute of its relation schema.

What is Relationship?
It is an association among two or more entities.

What is Relationship set? The collection (or set) of similar relationships.

Entity

2008-07-15T14:21:00.001+05:30

What is an Entity?
It is a 'thing' in the real world with an independent existence.

What is an Entity type?
It is a collection (set) of entities that have same attributes.

What is an Entity set?
It is a collection of all entities of particular entity type in the database.

What is an Extension of entity type?
The collections of entities of a particular entity type are grouped together into an entity set.

What is Weak Entity set?
An entity set may not have sufficient attributes to form a primary key, and its primary key compromises of its partial key and primary key of its parent entity, then it is said to be Weak Entity set.

ER Model and OOM

2008-07-15T14:20:00.001+05:30

What is E-R model?
This data model is based on real world that consists of basic objects called entities and of relationship among these objects. Entities are described in a database by a set of attributes.

What is Object Oriented model?
This model is based on collection of objects. An object contains values stored in instance variables with in the object. An object also contains bodies of code that operate on the object. These bodies of code are called methods. Objects that contain same types of values and the same methods are grouped together into classes.

View And Data Model

2008-07-15T14:19:00.004+05:30

What is a view? How it is related to data independence?
A view may be thought of as a virtual table, that is, a table that does not really exist in its own right but is instead derived from one or more underlying base table. In other words, there is no stored file that direct represents the view instead a definition of view is stored in data dictionary.
Growth and restructuring of base tables is not reflected in views. Thus the view can insulate users from the effects of restructuring and growth in the database. Hence accounts for logical data independence.

What is Data Model?
A collection of conceptual tools for describing data, data relationships data semantics and constraints.

Data Independence

2008-07-15T14:19:00.003+05:30

What is Data Independence?
Data independence means that “the application is independent of the storage structure and access strategy of data”. In other words, The ability to modify the schema definition in one level should not affect the schema definition in the next higher level.
Two types of Data Independence:
Ø Physical Data Independence: Modification in physical level should not affect the logical level.
Ø Logical Data Independence: Modification in logical level should affect the view level.
NOTE: Logical Data Independence is more difficult to achieve

Data Strudcture

2008-07-15T14:19:00.001+05:30

How is the data structure of System R different from the relational structure?
Unlike Relational systems in System R

Ø Domains are not supported
Ø Enforcement of candidate key uniqueness is optional
Ø Enforcement of entity integrity is optional
Ø Referential integrity is not enforced

System Resource

2008-07-15T14:18:00.003+05:30

What is System R? What are its two major subsystems?
System R was designed and developed over a period of 1974-79 at IBM San Jose Research Center. It is a prototype and its purpose was to demonstrate that it is possible to build a Relational System that can be used in a real life environment to solve real life problems, with performance at least comparable to that of existing system.
Its two subsystems are
Ø Research Storage
Ø System Relational Data System.

Extension and Intention

2008-07-15T14:18:00.001+05:30

1. What is extension and intension?
Extension -
It is the number of tuples present in a table at any instance. This is time dependent.
Intension -
It is a constant value that gives the name, structure of table and the constraints laid on it.

Rules

2008-07-15T14:17:00.003+05:30

Define the "integrity rules"

There are two Integrity rules.
Ø Entity Integrity: States that “Primary key cannot have NULL value”
Ø Referential Integrity: States that “Foreign Key can be either a NULL value or should be Primary Key value of other relation.

Data Abstraction

2008-07-15T14:17:00.001+05:30

Describe the three levels of data abstraction?

The are three levels of abstraction:
Ø Physical level: The lowest level of abstraction describes how data are stored.
Ø Logical level: The next higher level of abstraction, describes what data are stored in database and what relationship among those data.
Ø View level: The highest level of abstraction describes only part of entire database.

Advantages and Disadvantage of Dbms

2008-07-15T14:16:00.001+05:30

1. What is a Database system?
The database and DBMS software together is called as Database system.

2. Advantages of DBMS?
Ø Redundancy is controlled.
Ø Unauthorised access is restricted.
Ø Providing multiple user interfaces.
Ø Enforcing integrity constraints.
Ø Providing backup and recovery.

3. Disadvantage in File Processing System?
Ø Data redundancy & inconsistency.
Ø Difficult in accessing data.
Ø Data isolation.
Ø Data integrity.
Ø Concurrent access is not possible.
Ø Security Problems.

DBMS

2008-07-15T14:15:00.002+05:30

What is DBMS?

It is a collection of programs that enables user to create and maintain a database. In other words it is general-purpose software that provides the users with the processes of defining, constructing and manipulating the database for various applications

Database

2008-07-15T14:15:00.001+05:30

RDBMS Concepts
What is database?
A database is a logically coherent collection of data with some inherent meaning, representing some aspect of real world and which is designed, built and populated with data for a specific purpose.

sql help

2008-07-15T14:13:00.000+05:30

1. To see current user name Sql> show user;
2. Change SQL prompt name SQL> set sqlprompt “Manimara > “ Manimara > Manimara >
3. Switch to DOS prompt SQL> host
4. How do I eliminate the duplicate rows ? SQL> delete from table_name where rowid not in (select max(rowid) from table group by duplicate_values_field_name); or SQL> delete duplicate_values_field_name dv from table_name ta where rowid <(select min(rowid) from table_name tb where ta.dv=tb.dv); Example. Table Emp Empno Ename 101 Scott 102 Jiyo 103 Millor 104 Jiyo 105 Smith delete ename from emp a where rowid < ( select min(rowid) from emp b where a.ename = b.ename); The output like, Empno Ename 101 Scott 102 Millor 103 Jiyo 104 Smith
5. How do I display row number with records? To achive this use rownum pseudocolumn with query, like SQL> SQL> select rownum, ename from emp; Output: 1 Scott 2 Millor 3 Jiyo 4 Smith
6. Display the records between two range select rownum, empno, ename from emp where rowid in (select rowid from emp where rownum <=&upto minus select rowid from emp where rownum<&Start); Enter value for upto: 10 Enter value for Start: 7
ROWNUM EMPNO ENAME --------- --------- ---------- 1 7782 CLARK 2 7788 SCOTT 3 7839 KING 4 7844 TURNER

More about Scanner

2008-07-15T14:09:00.000+05:30

There are several different types of scanner, but they all work in the same way.
The most popular ones are flatbed scanners, which look a bit like photocopiers
You open up a lid, place the document you want to scan on a piece of glass and then close the lid again.
When you tell the computer to scan, the scanner moves its scanning head from side to side and progressively down the page until it's covered the entire printed area.
The scanning head contains a very bright light and a light-sensing unit called a CCD (charge-coupled display), side by side.
The CCD is the same sort of light detector that you find in a digital camera.
It detects the pattern of light being reflected into it off the printed page and produces a series of electrical signals.

How Analytic Functions Work

2008-07-15T14:07:00.000+05:30

Analytic functions compute an aggregate value based on a group of rows. They differ from aggregate functions in that they return multiple rows for each group. The group of rows is called a window and is defined by the analytic clause. For each row, a "sliding" window of rows is defined. The window determines the range of rows used to perform the calculations for the "current row". Window sizes can be based on either a physical number of rows or a logical interval such as time.

Analytic functions are the last set of operations performed in a query except for the final ORDER BY clause. All joins and all WHERE, GROUP BY, and HAVING clauses are completed before the analytic functions are processed. Therefore, analytic functions can appear only in the select list or ORDER BY clause.

Discuss Various Data Types in Oracle.

2008-07-15T09:56:00.000+05:30

Data types come in several forms and sizes, allowing the programmer to create tables suited according to the project requirement.
It is important to know which data type should be used where and what its width should be given.
CHAR:

This data type is used to store character strings values of fixed length.
The size in brackets determines how many characters can be accommodated or held in particular column.
The maximum number of characters that can be hold in this data type is 255 characters.
The data held inside the particular column is always right padded to the length/size specified. Ex if the length of particular column is 30 and we are only entering 10 character name then remaining 20 character space will occupied by blank space.
It occupies more space in memory.
It is always specified inside in single quotes while inserting records in the table.

VARCHAR:

This data type is used to store variable length alphanumeric data.
It is more flexible form of CHAR data type.
The maximum this data type can hold up to 4000 characters.
The only difference between VARCHAR and CHAR data type is that this is not padded with length/size specified.Ex if the length of particular column is 30 and we are entering only 10 character name then remaining 20 characters space is not occupied by blank space.
It occupies less space in memory as compared to CHAR data type.
VARCHAR is usually wiser choice than CHAR due to its variable length format characteristics.
CHAR is much faster than VARCHAR.
It is always specified inside in single quotes while inserting records in the table.

DATE:

This data type is used to store date and time.
The standard format is DD-MON-YY as 15-JAN-08.
To enter dates other than standard format, use the appropriate functions.
The time is stored in 24-hour format.
By default the time in a date field is 12:00:00 am if no portion is specified.
The default date is the first day of the current month.
Valid dates range from January 1, 4712 B.C to December 31, 4712 A.D
It is always specified inside the single quotes while inserting records in a table.

NUMBER:

This data type is used to store numbers (fixed or floating point number).
Numbers up to 38 digits of precision can be stored.
Valid values are 0, positive and negative numbers with magnitude 1.0E-130 to 9.9…E125.
The precision (P) determines the maximum length of data whereas the scale (S) determines the number of places to the right of the decimal.
If the scale is omitted then the default value is zero.
If the precision is omitted then values are stored with their original precision up to maximum of 38 digits.
It is specified without any single quotes while entering records in a table.

LONG:

This data type is used to store variable length character strings containing up to 2 GB.
LONG data can be used to store arrays of binary data in ASCII format.
Only one LONG value can be defined per table.
It cannot be used in sub queries, functions, expressions, where clauses or indexes and the normal character functions such as SUBSTR cannot be applied to LONG values.
A table containing LONG value cannot be clustered.

RAW/LONG RAW:

This data type is used store binary data such as digitized image or image.
Data stored into the columns of these data types are stored without any further conversion.
RAW data type can have maximum length of 255 bytes.
LONG RAW data type can contain up to 2 GB.LONG RAW data type cannot be indexed.