PHP Interview Questions - Set-1

1. Who is the father of PHP and explain the changes in PHP versions?

2. How can we submit a form without a submit button?

3. In how many ways we can retrieve the date in the result set of mysql using PHP?

4. What is the difference between mysql_fetch_object and mysql_fetch_array?

5. What is the difference between $message and $$message?

6. How can we extract string ‘abc.com ‘ from a string using regular expression of PHP?

7. How can we create a database using PHP and mysql?

8. What are the differences between require and include, include_once?

9. Can we use include (”abc.PHP”) two times in a PHP page “makeit.PHP”?

10. What are the different tables present in mysql, which type of table is generated when we are creating  a table in the following syntax: create table employee(eno int(2),ename varchar(10)) ?

11. Functions in IMAP, POP3 AND LDAP?

12. How can I execute a PHP script using command line?

13. Suppose your Zend engine supports the mode Then how can u configure your PHP Zend engine to support mode ?

14. What is meant by nl2br()?

15. Draw the architecture of Zend engine?

16. What are the current versions of apache, PHP, and mysql?

17. What are the reasons for selecting lamp (linux, apache, mysql, PHP) instead of combination of other software programmes, servers and operating systems?

18. How can we encrypt and decrypt a data present in a mysql table using mysql?

19. How can we encrypt the username and password using PHP?

20. What are the features and advantages of object-oriented programming?

21. What are the differences between procedure-oriented languages and object-oriented languages?

22. What is the use of friend function?

23. What are the differences between public, private, protected, static, transient, final and volatile?

24. What are the different types of errors in PHP?

25. What is the functionality of the function strstr and stristr?

26. What are the differences between PHP 3 and PHP 4 and PHP 5?

27. How can we convert asp pages to PHP pages?

28. What is the functionality of the function htmlentities?

29. How can we get second of the current time using date function?

Interview Questions .NET Windows Forms

1. 1. Write a simple Windows Forms MessageBox statement.

               a. System.Windows.Forms.MessageBox.Show
   
   
   
   

                b. ("Hello, Windows Forms");

   2. Can you write a class without specifying namespace? Which namespace does it belong to by default?
   Yes, you can, then the class belongs to global namespace which has no name. For commercial products, naturally, you wouldn’t want global namespace.
   3. You are designing a GUI application with a window and several widgets on it. The user then resizes the app window and sees a lot of grey space, while the widgets stay in place. What’s the problem?
   One should use anchoring for correct resizing. Otherwise the default property of a widget on a form is top-left, so it stays at the same location when resized.
   4. How can you save the desired properties of Windows Forms application?
   .config files in .NET are supported through the API to allow storing and retrieving information. They are nothing more than simple XML files, sort of like what .ini files were before for Win32 apps.
   5. So how do you retrieve the customized properties of a .NET application from XML .config file?
   Initialize an instance of AppSettingsReader class. Call the GetValue method of AppSettingsReader class, passing in the name of the property and the type expected. Assign the result to the appropriate variable.
   6. Can you automate this process?
    In Visual Studio yes, use Dynamic Properties for automatic .config creation, storage and retrieval.
   7. My progress bar freezes up and dialog window shows blank, when an intensive background process takes over.
    Yes, you should’ve multi-threaded your GUI, with taskbar and main form being one thread, and the background process being the other.
   8. What’s the safest way to deploy a Windows Forms app?
   Web deployment: the user always downloads the latest version of the code; the program runs within security sandbox, properly written app will not require additional security privileges.
   9. Why is it not a good idea to insert code into InitializeComponent method when working with Visual Studio?
   The designer will likely throw it away; most of the code inside InitializeComponent is auto-generated.
   10. What’s the difference between WindowsDefaultLocation and WindowsDefaultBounds?
   WindowsDefaultLocation tells the form to start up at a location selected by OS, but with internally specified size. WindowsDefaultBounds delegates both size and starting position choices to the OS.
   11. What’s the difference between Move and LocationChanged? Resize and SizeChanged?
   Both methods do the same, Move and Resize are the names adopted from VB to ease migration to C#.
   12. How would you create a non-rectangular window, let’s say an ellipse?
   Create a rectangular form, set the TransparencyKey property to the same value as BackColor, which will effectively make the background of the form transparent. Then set the FormBorderStyle to FormBorderStyle.None, which will remove the contour and contents of the form.
   13. How do you create a separator in the Menu Designer?
         A hyphen ‘-’ would do it. Also, an ampersand ‘&\’ would underline the next letter.
   14. How’s anchoring different from docking?
   Anchoring treats the component as having the absolute size and adjusts its location relative to the parent form. Docking treats the component location as absolute and disregards the component size. So if a status bar must always be at the bottom no matter what, use docking. If a button should be on the top right, but change its position with the form being resized, use anchoring. 

PHP Questions And Answers Set - 2

How do you start MySQL on Linux?
/etc/init.d/mysql start

Explain the difference between mysql and mysql interfaces in PHP?
mysqli is the object-oriented version of mysql library functions.

What?s the default port for MySQL Server?
3306

What does tee command do in MySQL?
tee followed by a filename turns on MySQL logging to a specified file. It can be stopped by command note.

Can you save your connection settings to a conf file?
Yes, and name it ~/.my.conf. You might want to change the permissions on the file to 600, so that it?s not readable by others.

How do you change a password for an existing user via mysqladmin?
mysqladmin -u root -p password "newpassword"

Use mysqldump to create a copy of the database?
mysqldump -h mysqlhost -u username -p mydatabasename > dbdump.sql

Have you ever used MySQL Administrator and MySQL Query Browser?
Describe the tasks you accomplished with these tools.

What are some good ideas regarding user security in MySQL?
There is no user without a password. There is no user without a user name. There is no user whose Host column contains % (which here indicates that the user can log in from anywhere in the network or the Internet). There are as few users as possible (in the ideal case only root) who have unrestricted access.

Explain the difference between MyISAM Static and MyISAM Dynamic. ?
In MyISAM static all the fields have fixed width. The Dynamic MyISAM table would include fields such as TEXT, BLOB, etc. to accommodate the data types with various lengths. MyISAM Static would be easier to restore in case of corruption, since even though you might lose some data, you know exactly where to look for the beginning of the next record.

What does myisamchk do?It compressed the MyISAM tables, which reduces their disk usage.

Explain advantages of InnoDB over MyISAM?
Row-level locking, transactions, foreign key constraints and crash recovery.

Explain advantages of MyISAM over InnoDB?
Much more conservative approach to disk space management - each MyISAM table is stored in a separate file, which could be compressed then with myisamchk if needed. With InnoDB the tables are stored in tablespace, and not much further optimization is possible. All data except for TEXT and BLOB can occupy 8,000 bytes at most. No full text indexing is available for InnoDB. TRhe COUNT(*)s execute slower than in MyISAM due to tablespace complexity

What are HEAP tables in MySQL?
HEAP tables are in-memory. They are usually used for high-speed temporary storage. No TEXT or BLOB fields are allowed within HEAP tables. You can only use the comparison operators = and <=>. HEAP tables do not support AUTO_INCREMENT. Indexes must be NOT NULL.

How do you control the max size of a HEAP table?
MySQL config variable max_heap_table_size.

What are CSV tables?Those are the special tables, data for which is saved into comma-separated values files. They cannot be indexed.

Explain federated tables. ?
Introduced in MySQL 5.0, federated tables allow access to the tables located on other databases on other servers.

What is SERIAL data type in MySQL?
BIGINT NOT NULL PRIMARY KEY AUTO_INCREMENT

What happens when the column is set to AUTO INCREMENT and you reach the maximum value for that table?
It stops incrementing. It does not overflow to 0 to prevent data losses, but further inserts are going to produce an error, since the key has been used already.

Explain the difference between BOOL, TINYINT and BIT. ?
Prior to MySQL 5.0.3: those are all synonyms. After MySQL 5.0.3: BIT data type can store 8 bytes of data and should be used for binary data.

Explain the difference between FLOAT, DOUBLE and REAL. ?
FLOATs store floating point numbers with 8 place accuracy and take up 4 bytes. DOUBLEs store floating point numbers with 16 place accuracy and take up 8 bytes. REAL is a synonym of FLOAT for now.

If you specify the data type as DECIMAL (5,2), what?s the range of values that can go in this table?
999.99 to -99.99. Note that with the negative number the minus sign is considered one of the digits.

What happens if a table has one column defined as TIMESTAMP?
That field gets the current timestamp whenever the row gets altered.

But what if you really want to store the timestamp data, such as the publication date of the article?
Create two columns of type TIMESTAMP and use the second one for your real data.

Explain data type TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP ?
The column exhibits the same behavior as a single timestamp column in a table with no other timestamp columns.

What does TIMESTAMP ON UPDATE CURRENT_TIMESTAMP data type do?
On initialization places a zero in that column, on future updates puts the current value of the timestamp in.

Explain TIMESTAMP DEFAULT ?2006:09:02 17:38:44? ON UPDATE CURRENT_TIMESTAMP. ?
A default value is used on initialization, a current timestamp is inserted on update of the row.

If I created a column with data type VARCHAR(3), what would I expect to see in MySQL table?
CHAR(3), since MySQL automatically adjusted the data type.

General Information About MySQLMySQL is a very fast, multi-threaded, multi-user, and robust SQL (Structured Query Language) database server.

MySQL is free software. It is licensed with the GNU GENERAL PUBLIC LICENSE http://www.gnu.org/.

What Is MySQL
MySQL, the most popular Open Source SQL database, is provided by MySQL AB. MySQL AB is a commercial company that builds is business providing services around the MySQL database. See section 1.2 What Is MySQL AB.

SQL is a database management system.
A database is a structured collection of data. It may be anything from a simple shopping list to a picture gallery or the vast amounts of information in a corporate network. To add, access, and process data stored in a computer database, you need a database management system such as MySQL. Since computers are very good at handling large amounts of data, database management plays a central role in computing, as stand-alone utilities, or as parts of other applications

PHP Questions And Answers Set - 1

What's PHP ?
The PHP Hypertext Preprocessor is a programming language that allows web developers to create dynamic content that interacts with databases. PHP is basically used for developing web based software applications.

What Is a Session?
A session is a logical object created by the PHP engine to allow you to preserve data across subsequent HTTP requests.

There is only one session object available to your PHP scripts at any time. Data saved to the session by a script can be retrieved by the same script or another script when requested from the same visitor.

Sessions are commonly used to store temporary data to allow multiple PHP pages to offer a complete functional transaction for the same visitor.

What is meant by PEAR in php?
Answer:

PEAR is the next revolution in PHP. This repository is bringing higher level programming to PHP. PEAR is a framework and distribution system for reusable PHP components. It eases installation by bringing an automated wizard, and packing the strength and experience of PHP users into a nicely organised OOP library. PEAR also provides a command-line interface that can be used to automatically install "packages"


PEAR is short for "PHP Extension and Application Repository" and is pronounced just like the fruit. The purpose of PEAR is to provide:
A structured library of open-sourced code for PHP users
A system for code distribution and package maintenance
A standard style for code written in PHP
The PHP Foundation Classes (PFC),
The PHP Extension Community Library (PECL),
A web site, mailing lists and download mirrors to support the PHP/PEAR community
PEAR is a community-driven project with the PEAR Group as the governing body. The project has been founded by Stig S. Bakken in 1999 and quite a lot of people have joined the project since then.

How can we know the number of days between two given dates using PHP?
Simple arithmetic:

$date1 = date('Y-m-d');
$date2 = '2006-07-01';
$days = (strtotime() - strtotime()) / (60 * 60 * 24);
echo "Number of days since '2006-07-01': $days";

What is the difference between $message and $$message?
Anwser 1:
$message is a simple variable whereas $$message is a reference variable. Example:
$user = 'bob'

is equivalent to

$holder = 'user';
$$holder = 'bob';


They are both variables. But $message is a variable with a fixed name. $$message is a variable who's name is stored in $message. For example, if $message contains "var", $$message is the same as $var.

What Is a Persistent Cookie?
A persistent cookie is a cookie which is stored in a cookie file permanently on the browser's computer. By default, cookies are created as temporary cookies which stored only in the browser's memory. When the browser is closed, temporary cookies will be erased. You should decide when to use temporary cookies and when to use persistent cookies based on their differences:
*Temporary cookies can not be used for tracking long-term information.
*Persistent cookies can be used for tracking long-term information.
*Temporary cookies are safer because no programs other than the browser can access them.
*Persistent cookies are less secure because users can open cookie files see the cookie values.

What does a special set of tags <?= and ?> do in PHP?
The output is displayed directly to the browser.  

How do you define a constant?
Via define() directive, like define ("MYCONSTANT", 100);

What are the differences between require and include, include_once?
Anwser 1:
require_once() and include_once() are both the functions to include and evaluate the specified file only once. If the specified file is included previous to the present call occurrence, it will not be done again.

But require() and include() will do it as many times they are asked to do.


The include_once() statement includes and evaluates the specified file during the execution of the script. This is a behavior similar to the include() statement, with the only difference being that if the code from a file has already been included, it will not be included again. The major difference between include() and require() is that in failure include() produces a warning message whereas require() produces a fatal errors.


All three are used to an include file into the current page.
If the file is not present, require(), calls a fatal error, while in include() does not.
The include_once() statement includes and evaluates the specified file during the execution of the script. This is a behavior similar to the include() statement, with the only difference being that if the code from a file has already been included, it will not be included again. It des not call a fatal error if file not exists. require_once() does the same as include_once(), but it calls a fatal error if file not exists.


File will not be included more than once. If we want to include a file once only and further calling of the file will be ignored then we have to use the PHP function include_once(). This will prevent problems with function redefinitions, variable value reassignments, etc.

What is the difference between mysql_fetch_object and mysql_fetch_array?
MySQL fetch object will collect first single matching record where mysql_fetch_array will collect all matching records from the table in an array

How can I execute a PHP script using command line?
Just run the PHP CLI (Command Line Interface) program and provide the PHP script file name as the command line argument. For example, "php myScript.php", assuming "php" is the command to invoke the CLI program.
Be aware that if your PHP script was written for the Web CGI interface, it may not execute properly in command line environment.

I am trying to assign a variable the value of 0123, but it keeps coming up with a different number, what?s the problem?
PHP Interpreter treats numbers beginning with 0 as octal. Look at the similar PHP interview questions for more numeric problems.

Would I use print "$a dollars" or "{$a} dollars" to print out the amount of dollars in this example?
In this example it wouldn?t matter, since the variable is all by itself, but if you were to print something like "{$a},000,000 mln dollars", then you definitely need to use the braces.

What are the different tables present in MySQL? Which type of table is generated when we are creating a table in the following syntax: create table employee(eno int(2),ename varchar(10))?
Total 5 types of tables we can create
1. MyISAM
2. Heap
3. Merge
4. INNO DB
5. ISAM
MyISAM is the default storage engine as of MySQL 3.23. When you fire the above create query MySQL will create a MyISAM table.

ASP.NET Question/Answer Set-2

2.1 Describe the security authentication flow and process in ASP.NET? 

When a user requests a web page, there exists a process of security too, so that every anonymous user is checked for authentication before gaining access to the webpage. The following points are followed in the sequence for authentication when a client attempts a page request:

* A .aspx web page residing on an IIS web server is requested by an end user
* IIS checks for the user's credentials
* Authentication is done by IIS. If authenticated, a token is passed to the ASP.NET worker process along with the request
* Based on the authentication token from IIS, and on the web.config settings for the requested resource, ASP.NET impersonates the end user to the request thread. For impersonation, the web.config impersonate attribute's value is checked. 
2.2 What is the Website Administrative Tool in ASP.NET 2.0 ? 
In ASP.NET 2.0, while using Visual Studio 2005 Express Edition or above, the development IDE provides an interface for editing the web.config rather than manually editing the web.config. 

In the IDE, click on "Website" and then on "ASP.NET Configuration". This shall open the Website configuration tool. Note that the Web Site Administration Tool is a set of prebuilt ASP.NET 2.0 webpages and resources that are located within the C:\Inetpub\wwwroot\aspnet_webadmin\2_0_40607 directory. 

2.3 What is Authentication? What are the different types of Authentication? 
In a client-server environment, there are plenty of cases where the server has to interact and identify the client that sends a request to the server. Authentication is the process of determining and confirming the identity of the client. 

If a client is not successfully identified, it is said to be anonymous. 
Types of Authentication
Windows Authentication
Forms Authentication
Passport Authentication

Essentially the Windows Authentication and Forms Authentication are the famous ones, as Passport Authentication is related to a few websites (like microsoft.com, hotmail.com, msn.com etc. only).

Windows Authentication is implemented mostly in Intranet scenarios. When a browser (client) sends a Request to a server where in windows authentication has been implemented, the initial request is anonymous in nature. The server sends back a Response with a message in HTTP Header. This Prompts a Window to display a Modal Dialog Box on the browser, where the end user may enter the "User name" and "Password". 

The end user enters the credentials, which are then validated against the User Store on the Windows server. Note that each user who access the Web Application in a Windows Authentication environment needs to have a Windows Account in the company network. 

2.4 How to avoid or disable the modal dialog box in a Windows Authentication environment? 

By enabling the Windows Integrated Authentication checkbox for the web application through settings in IIS. 

Forms Authentication is used in Internet based scenarios, where its not practical to provide a Windows based account to each and every user to the Web Server. In a Forms Authentication environment, the user enters credentials, usually a User Name and a corresponding Password, which is validated against a User Information Store, ideally a database table. 

Forms Authentication Ticket is the cookie stored on the user's computer, when a user is authenticated. This helps in automatically logging in a user when he/she re-visits the website. When a Forms Authentication ticket is created, when a user re-visits a website, the Forms Authentication Ticket information is sent to the Web Server along with the HTTP Request. 

2.5 What is Authorization in ASP.NET? 

Authorization, in simple words means "which user can access which resource on a web server". Authentication of users may be set in the web.config file. See web.config snippet below... 

Based on the user and the role, access to different folders across the website may be controlled using the authorization feature of ASP.NET 

2.6 What is IIS Metabase? How to edit IIS metabase? How to backup IIS metabase file? 
IIS Metabase - sounds like geek stuff right! What is IIS Metabase??? In the simplest words, IIS metabase is the repository of the configuration values that are set in the Internet Information Server (IIS). The IIS metabase in an XML file. It may be controlled through program or manually too. 

In order to edit IIS metabase entries, the user needs to have administrative rights on the system. To do this, in run window, type "inetmgr". Browse to "Local Computer" and right click it. Click on "Properties". Select the "Enable Direct Metabase Edit" check box.

Many times, due to the existence of multiple versions of .NET framework, some settings in the IIS metabase may get affected and cause your program not to run. For such scenarios, you may take a backup of the IIS metabase XML file and recover it. To create a portable backup, open run window and type "inetmgr". Next browse to "Local Computer" and go to "All Tasks". Next, click on Backup/Restore Configuration. Next, click on "Create Backup". In the textbod box for Configuration Backup name, type a name for your backup file. Also select the encrypt backup option and type a password. To finish the process, click "OK". 

Search for Metabase.xml file on your IIS Web Server.

2.7 What is mixed mode authentication in ASP.NET? 
Mixed mode authentication in an asp.net web application has the ability to feature both Forms Authentication and Windows Authentication to the end user.

In such a web application, the website user is identified based on whether the user is accessing the site from within the local domain or an external domain. When the user is from within the domain, Windows Authentication is applied and thus, the user can be configured to have higher authorization rights. The users logging into the web application from an external domain access the site using Forms authentication. 

But this is tricky!!! For such an application to work, there needs to be 2 virtual directories setup for the web application on the IIS. This is because an asp.net web application cannot be set to two different authentication modes. 
So if someone asks Can an ASP.NET application support 2 authentication modes at the same time??? 
the answer is TECHNICALLY NO!, but there is a workaround!!! ... there are always workarounds for everything in ASP.NET... its so powerful! 
The windows authentication site's authentication information is basically used to get information about the intranet users and this is passed to the web application for Forms authentication. In such a scenario, the windows authentication information from the windows authentication site in IIS is passed to the Forms Authentication and thus user role is verified

ASP.NET Question/Answer Set-1

ASP.NET
1.1 Whats the difference between Classic ASP and ASP.NET? 

Major difference: Classic ASP is Interpreted. ASP.NET is Compiled. If code is changed, ASP.NET recompiles, otherwise does'nt.
Other differences: ASP works with VB as the language. ASP.NET works with VB.NET & C# as the languages (Also supported by other languages that run on the .NET Framework). 
ASP.NET is the web technology that comes with the Microsoft .NET Framework. The main process in ASP.NET is called aspnet_wp.exe that accesses system resources. ASP.NET was launched in 2002 with version 1.0. Subsequent versions are 1.1 and version 2.0. ASP.NET is built up using thousands of objects, ordered in the System namespace. When an ASP.NET class is compiled, its called an assembly. 
In Classic ASP, complex functionalities are achieved using COM components, that are nothing but component objects created using VB 6, C++ etc, and are usually in a DLL format. These components provide an exposed interface to methods in them, to the objects that reference these components. Last version of classic ASP is version 3.0. ASP has 7 main objects - Application, ASPError, ObjectContext, Request, Response, Server, Session. 

1.2 How to redirect a page to another page? 

The Response object has a famous Redirect method that is used most widely to transfer a web page visitor from one page to another page. 
Syntax of Response.Redirect ...

Response.Redirect("DestinationPage.aspx") 
There is another famous method called Transfer method of the Server object. 
Syntax of Server.Transfer ...

Server.Transfer("DestinationPage.aspx") 

1.3 How to pass values between pages? 

There are several methods to pass values from one page to another page. Described below are few methods to pass values between pages:

QueryString - The QueryString method of passing values between web pages is one of the oldest methods of passing values between pages. A variable value is properly encoded before it is placed on a querystring. This is to make sure that characters that cause problems (like symbols and spaces) are encoded correctly. See the code below to see how QueryString functionality works.
//Code in InitialPage.aspx
String sString;
sString = Server.UrlEncode("string in InitialPage.aspx");
Response.Redirect("DestinationPage.aspx?Value=" & sString);

//Code in DestinationPage.aspx reads the QueryString
String sString;
sString = Request.QueryString("Value");
Response.Write("Your name is " & sString);

The data in the DestinationPage.aspx in the URL looks like this...

http://www.dotnetuncle.com/DestinationPage.aspx?Value=dotnetUncle 
Context - The context object is used to send values between pages. Its similar to the session object, the difference being that, the Context object goes out of scope when the page is sent to a browser. Example code below shows how to use Context object. 
'InitialPage.aspx stores value in context before sending it
Context.Items("MyData") = "dotnetuncle";
Server.Transfer("DestinationPage.aspx");

'DestinationPage.aspx retrieves the value from InitialPage.aspx's context
String sString;
sString = Context.Items("MyDate").ToString;
Response.Write("The data is as follows: " & sString);
Session - The session object is used to persist data across a user session during the user's visit to a website. It is almost same as the Context object. When we use Response.Redirect, it causes the Context object to go away, so rather the Session object is used in such a scenario. Session object uses more of server memory than a context object. Example code below shows how to use Session object. 
'InitialPage.aspx stores value in session before sending it
Session.Items("MyData") = "dotnetuncle";
Response.Redirect("DestinationPage.aspx");

'DestinationPage.aspx retrieves the value from InitialPage.aspx's session
String sString;
sString = Session.Items("MyDate").ToString;
Response.Write("The data is as follows: " & sString);
You may notice above, I have used Response.Redirect with session object, and server.transfer with a context object.

How do you turn off SessionState in the web.config file? 
In the system.web section of web.config, you should locate the httpmodule tag and you simply disable session by doing a remove tag with attribute name set to session.






1.4 How to sort the contents of a GridView control? 

The ASP.NET 2.0 GridView control is a powerful control, the enables sorting of the rows based on a column, all this possible, without writing code. Well thats what we call power! 

The GridView control relies on the underlying data source control to whom this is bound for the sorting capability. The GridView needs to have an AccessDataSource or an SQlDataSource or an ObjectDataSource (if the SortParameterName property is set to a value allowed. 

The AllowSorting property of the GridView control, when set to true, enables sorting of the GridView. A sortable GridView has the Header column represented as a LinkButton control. When this Link Button is clicked, the Sorting event of the GridView is raised server-side, which causes a postback and in turn, sorts the GridView control's records. 

1.29 What does the Hotspot class in .NET do? What is an ImageMap in ASP.NET?

An ImageMap is an ASP.NET control that allows clicks inside a polygon like (called Hotspot) region in a webpage. Well, that actually means you may create a star-shaped or diamond shaped button. Wow! 

There are several pre-defined shapes allowed inside an ImageMap for which templates may be used. For example, for a rectangle, an asp:RectangularHotSpot may be used. For a circle, an asp:CircleHotSpot may be used. And for creating stars & diamonds, an asp:PolygonHotSpot may be used. An image may also be put in an ImageMap which may be specified by its ImageUrl property. 

In order to invoke an event, the HotSpotMode property needs to be set to PostBack. Further, if several HotSpots are placed inside an ImageMap, the event of the ImageMap may be passed a value using the PostBackValue property. 
Code below shows how to create a Polygon HotSpot using an ImageMap.


ImageUrl="Photo.gif" OnClick="SomeEvent"
AlternateText="Click Here"
HotSpotMode="Navigate">


AlternateText="Click Here Too!"
Coordinates="100,150, 250,350, 210,290, 90,350, 60,240"
NavigateUrl="http://www.asp.net"
Target="_blank"/>

1.30 How do we update and delete data in a gridview? Datakeynames property in .NET? 
The best way to Update or Delete a record in a GridView control is to include a CheckBox column and a Submit Button. 

The GridView has its own Delete and Edit functionality. If the GridView is populated with data using an SqlDataSource, checkout the wizard that comes along with the SqlDataSource. It may be used to automatically create an SQL Delete command and specify the delete parameters. 

The DataKeyNames property of the GridView is set to a field name of the Table. 
1.31 How to add gridview/datagrid columns manually? Autogenerate in .NET? 
The datagrid (of ASP.NET 1.1) and gridview (of ASP.NET 2.0) has a property called AutoGenerateColumns. This property is set to false. After this, columns may be set manually. Sample source below... 

SelectCommand="SELECT [au_id], [au_lname], [au_fname], [phone], [address] FROM [authors]"
ConnectionString="" />