1 . What is ASP.NET?
ASP.NET is a programming
framework built on the common language runtime that can be used on a server to
build powerful Web applications
.
2 . Why does my ASP.NET file have multiple tag with
runat=server?
This means that ASP.Net is not
properly registered with IIS.
.Net framework provides an
Administration utility that manages the installation and uninstallation of
multiple versions of ASP.NET on a single machine. You can find the file in
C:\WINNT\Microsoft.NET\Framework\v**\aspnet_regiis.exe
use the command:
aspnet_regiis.exe -u ---> to uninstall current asp.net version.
use the command:
aspnet_regiis.exe -i ---> to install current asp.net version.
For Windows Server 2003, you
must use aspnet_regiis -i -enable
This is because of the
"Web Service Extensions" feature in IIS 6
(if you install VS.NET or the
framework without IIS installed, and then go back in and install IIS
afterwards, you have to re-register so that ASP.NET 'hooks' into IIS
properly."
3 . How to find out what version of ASP.NET I am using
on my machine?
VB.NET
Response.Write(System.Environment.Version.ToString()
)
C#
Response.Write(System.Environment.Version.ToString()
);
4 . Is it possible to pass a querystring from an .asp
page to aspx page?
Yes you can pass querystring
from .asp to ASP.NET page .asp
<%response.redirect
"webform1.aspx?id=11"%>
.aspx
VB.NET
Response.Write
(Request("id").ToString ())
C#
Response.Write
(Request["id"].ToString ());
5 . How to comment out ASP.NET Tags?
<%--<asp:Label
id="Label1" style="Z-INDEX: 101; LEFT: 8px; POSITION: absolute;
TOP: 48px" runat="server">Label</asp:Label>--%>
6 . What is a ViewState?
In classic ASP, when a form
is submitted the form values are cleared. In some cases the form is submitted
with huge information. In such cases if the
server comes back with error, one has to re-enter correct information in the
form. But submitting clears up all form values. This happens as the site does
not maintain any state (ViewState).
In ASP .NET, when the form is
submitted the form reappears in the browser with all form values. This is
because ASP .NET maintains your ViewState. ViewState is a state management
technique built in ASP.NET. Its purpose is to keep the state of controls during
subsequent postbacks by the same user. The ViewState indicates the status of
the page when submitted to the server. The status is defined through a hidden
field placed on each page with a <form runat="server"> control.
<input
type="hidden" name=
"__VIEWSTATE"value="dDwyNTA3OTU0NDM7Oz7t5TntzkOUeB0QVV6FT2hvQwtpPw=="
/>
If you want to NOT maintain
the ViewState, include the directive <%@ Page
EnableViewState="false"%> at the top of an .aspx page If you do
not want to maintain Viewstate for any control add the attribute
EnableViewState="false" to any control. For more details refer The
ASP.NET View State
7 . Where can I get the details on Migration of
existing projects using various technologies to ASP.NET?
Microsoft has designed
Migration Assistants to help us convert existing pages and applications to
ASP.NET. It does not make the conversion process completely automatic, but it
will speed up project by automating some of the steps required for migration.
Below are the Code Migration
Assistants
* ASP to ASP.NET Migration Assistant
* PHP to ASP.NET Migration Assistant
* JSP to ASP.NET Migration Assistant
Refer Migrating to ASP.Net
8 . What is the equivalent of date() and time() in
ASP.NET?
VB.NET
System.DateTime.Now.ToShortDateString()
System.DateTime.Now.ToShortTimeString()
C#
System.DateTime.Now.ToShortDateString();
System.DateTime.Now.ToShortTimeString();
9 . How to prevent a button from validating it's form?
Set the CauseValidation
property of the button control to False
10 . How to get the IP address of the host accessing
my site?
VB.NET
Response.Write
(Request.UserHostAddress.ToString ())
C#
Response.Write
(Request.UserHostAddress.ToString ());
>
11 . How to access the Parameters passed in via the
URL?
Call the
Request.QueryStringmethod passing in the key. The method will return the
parameter value associated with that key. VB.NET
Request.QueryString("id")
C#
Request.QueryString["id"];
12 . How to display a Wait page while a query is
running?
Refer Asynchronous Wait State
13 . How to implement Form based Authentication in
ASP.NET application?
For
* VB.NET
* C#
14 . How to catch the 404 error in my web application
and provide more useful information?
In the global.asax
Application_error Event write the following code
VB.NET
Dim ex As Exception =
Server.GetLastError().GetBaseException()
If TypeOf ex Is
System.IO.FileNotFoundException Then
'your code
'Response.Redirect("err404.aspx")
Else
'your code
End If
C#
Exception ex =
Server.GetLastError().GetBaseException();
if (ex.GetType() ==
typeof(System.IO.FileNotFoundException))
{
//your code
Response.Redirect
("err404.aspx");
}
else
{
//your code
}
15 . Is there a method similar to Response.Redirect
that will send variables to the destination page other than using a query
string or the post method?
Server.Transfer preserves the
current page context, so that in the target page you can extract values and
such. However, it can have side effects; because Server.Transfer doesnt' go
through the browser, the browser doesn't update its history and if the user
clicks Back, they go to the page previous to the source page.
Another way to pass values is
to use something like a LinkButton. It posts back to the source page, where you
can get the values you need, put them in Session, and then use
Response.Redirect to transfer to the target page. (This does bounce off the
browser.) In the target page you can read the Session values as required.
Refer to Passing Values
Between Web Forms Pages for more information.
16 . What are the differences between HTML versus
Server Control?
Refer
* ASP.NET Server Controls Recommendations
* Introduction to ASP.NET Server Controls
17 . How can I change the action of a form through
code?
You can't change it. The
action attribute is owned by ASP.NET. Handle Events and Transfer.
For work around refer to Paul
Wilson's Multiple Forms and Non-PostBack Forms - Solution
18 . Is there any control that allows user to select a
time from a clock - in other words is there a clock control?
Peter Blum has developed some
controls. Check out Peter's Date Package: TimeOfDayTextBox and DurationTextBox
Controls
19 . How to Compare time?
VB.NET
Dim t1 As String =
DateTime.Parse("3:30 PM").ToString("t")
Dim t2 As String =
DateTime.Now.ToString("t")
If
DateTime.Compare(DateTime.Parse(t1), DateTime.Parse(t2)) < 0 Then
Response.Write(t1.ToString() & "
is < than " & t2.ToString())
Else
Response.Write(t1.ToString() & "
is > than " & t2.ToString())
End If
C#
string t1 = DateTime.Parse("3:30
PM").ToString("t");
string t2 =
DateTime.Now.ToString("t");
if
(DateTime.Compare(DateTime.Parse (t1), DateTime.Parse (t2)) < 0 )
{
Response.Write(t1.ToString() + " is
< than " + t2.ToString());
}
else
{
Response.Write(t1.ToString() + " is >
than " + t2.ToString());
}
20 . How To work with TimeSpan Class?
VB.NET
Dim adate As DateTime =
DateTime.Parse("06/24/2003")
Dim bdate As DateTime =
DateTime.Parse("06/28/2003")
Dim ts As New
TimeSpan(bdate.Ticks - adate.Ticks)
Response.Write(ts.TotalDays
& "<br>")
Response.Write(ts.TotalHours
& ":" & ts.TotalMinutes & ":" &
ts.TotalSeconds & ":" & ts.TotalMilliseconds)
C#
DateTime adate =
DateTime.Parse("06/24/2003");
DateTime bdate =
DateTime.Parse("06/28/2003");
TimeSpan ts = new TimeSpan
(bdate.Ticks - adate.Ticks);
Response.Write(ts.TotalDays.ToString
() + "<br>");
Response.Write(ts.TotalHours.ToString()
+ ":" + ts.TotalMinutes.ToString() + ":" +
ts.TotalSeconds.ToString() + ":" + ts.TotalMilliseconds.ToString() );
21 . Where can I get information on Cookies in
ASP.NET?
Refer Mike Pope's article
Basics of Cookies in ASP.NET
22 . Does ASP.Net still recognize the global.asa file?
ASP.Net does not recognize
the standard ASP global.asa file. Instead it uses a file named global.asax with
the same - plus additional - functionality.
23 . How should I destroy my objects in ASP.Net?
ASP.Net actually has very
solid internal garbage collection. So this is not an issue as it was in
previous versions of Active Server Pages.
Link to more information:
<gcConcurrent> Element
24 . Are there resources online with tips on ASP to
ASP.Net conversions?
Microsoft has deisnged The
ASP to ASP.NET Migration Assistant help us convert ASP pages and applications
to ASP.NET. It does not make the conversion process completely automatic, but
it will speed up project by automating some of the steps required for
migration.
The following Code Migration
Assistants are discussed in the link below.
* ASP to ASP.NET Migration Assistant
* PHP to ASP.NET Migration Assistant
* JSP
to ASP.NET Migration Assistant
Refer Migrating to ASP.Net
Also refer:
* Microsoft's ASP to ASP.NET Code Migration
Assistant
* John Peterson's article Microsoft's ASP
to ASP.NET Migration Assistant
* Paolo Cavone's article From ASP to
ASP.NET... Painlessly!
25 . How do I publish my ASP.NET application to my
ISP's web server?
Your ISP must first create an
IIS application and apply the Front Page Server Extensions to it. Then in
Visual Studio .NET, select the "Project | Copy Project" menu. Then
enter the URL and select the FrontPage web access method. The "Copy
Project" feature copies all of the necessary files to your ISP's machine
for your ASP.NET application to run.
You can also FTP your files
to your ISP web server. But you must know which files to upload. For more
details refer PRB: Remote ASP.NET Projects Require IIS on the Client Computer
or FrontPage Server Extensions on the Server Computer
26 . Why do i get error message "Could not load
type" whenever I browse to my ASP.NET web site?
Your code-behind files for
either your .aspx or the global.aspx page have not been complied. Use Visual
Studio .NET's "Build | Build Solution" menu, or run the command line
compiler.
For more details refer PRB:
"Could not load type" error message when you browse to .aspx page
27 . Will the WebMatrix SqlDataSourceControl work with
a MySQL connection?
SqlDataSourceControl lets you
connect and work with MS SQL DB, while AccessDataSourceControl do the same
thing but for MS Access DB. Therefore SqlDataSourceControl can't help you in
your MySql connectivity .
For Connectivity with MySql
refer Accessing MySQL Database with ASP.NET
28 . Can I combine classic ASP and ASP.NET pages?
No.
ASP pages can run in the same
site as ASP.NET pages, but you can't mix in a page. Also ASP and ASP.NET won't
share their session.
29 . What is the difference between src and
Code-Behind?
Src attribute means you
deploy the source code files and everything is compiled JIT (just-in-time) as
needed. Many people prefer this since they don't have to manually worry about
compiling and messing with dlls -- it just works. Of course, the source is now
on the server, for anyone with access to the server -- but not just anyone on
the web.
CodeBehind attribute doesn't
really "do" anything, its just a helper for VS.NET to associate the
code file with the aspx file. This is necessary since VS.NET automates the
pre-compiling that is harder by hand, and therefore the Src attribute is also
gone. Now there is only a dll to deploy, no source, so it is certainly better
protected, although its always decompilable even then.
30 . How can I get the value of input box with type
hidden in code-behind?
You can set the runat= server
for the hidden control and you can use ControlName.Value to get its value in
CodeBehind file
>
31 . I have created a .NET user control page (.ascx)
but I cannot compile and run it.
User control (ascx) can't be
run on it own, but you can drag it onto any web page (aspx) and then run it.
32 . What is a .resx file?
The .resx resource file
format consists of XML entries, which specify objects and strings inside XML
tags. This is useful for localization. For more details refer Resources in
.resx files
33 . Is it possible to use a style sheet class
directly on a control instead of using inline or page-level formatting ?
Every WebControl derived
control has a CssClass property which allows you to set it's format to a style
sheet.
34 . Can I recieve both HTML markup for page and code
in the ASP.NET web page's source code portion in the Web browser?
No. The Web browser recieves
only HTML markup.
No source code or web control
syntax is passed back to the web browser.
35 . Why can't I put <%@ Page Language="C
" %> where at the top of an ASPX file and write my server-side scripts
in C ?
The parsers ASP.NET uses to
extract code from ASPX files understand C#, Visual Basic.NET, and JScript.NET.
You can write server-side scripts in any language supported by a .NET compiler.
36 . ASP pages that worked pefectly on Windows 2000
Server and IIS 5.0 do not work on Windows 2003 Server with IIS 6.0. ASP.NET
pages work fine. Why?
Start -> Settings ->
Control Panel -> Administrative Tools -> and double clicking IIS Manager.
Go to the Web Service
Extensions tab, click Active Server Pages, then press the "Allow"
button on the left
37 . Why do I get error message "Error creating
assembly manifest: Error reading key file 'key.snk' -- The system cannot find
the file specified"?
Check the location of the
key.snk file relative to the assembly file. Provide an explicit path or a
relative path.
<Assembly:
AssemblyKeyFileAttribute("Drive:\key.snk")>
38 . How to get URL without querystring?
VB.NET
Dim stringUri As String =
"http://www.syncfusion.com/?id=1&auid=16"
Dim weburi As Uri = New
Uri(stringUri)
Dim query As String =
weburi.Query
Dim weburl As String =
stringUri.Substring(0, stringUri.Length - query.Length)
Response.Write(weburl)
C#
string stringUri =
"http://www.syncfusion.com/?id=1&auid=16";
Uri weburi = new
Uri(stringUri);
string query = weburi.Query;
string weburl =
stringUri.Substring(0, stringUri.Length - query.Length);
Response.Write (weburl);
39 . What is the best way to output only time and not
Date?
Use DateTime as follows
VB.NET
Response.Write(DateTime.Now.ToString("hh:mm:ss"))
C#
Response.Write(DateTime.Now.ToString("hh:mm:ss"));
40 . Do I have to compile code if I am changing the
content of my aspx.cs file?
Yes if you have used
Codebehind="my.aspx.cs".
Not if you used
src="my.aspx.cs" in your page declaration.
>
41 . How to grab the referring URL?
VB.NET
Response.Write (
Request.UrlReferrer.ToString())
C#
Response.Write (
Request.UrlReferrer.ToString());
42 . My ASP code gives an error "Compiler Error
Message: BC30289: Statement cannot appear within a method body. End of method
assumed" when changed to .aspx?
Use a <script
runat=server> block instead of the <% %> syntax to define Subs.
Make sure you have proper
events associated with the code and have start and end of procedure or function
wirtten properly.
43 . How can I save images ?
You need a stream to read the
response, WebResponse.GetResponseStream(), and a stream to write it to the hard
drive. FileStream should do the trick. You'll have to write to the filestream
what you read from the response stream.
44 . How can I logout when using FormsAuthentication?
FormsAuthentication.SignOut()
45 . Why do I get a blank page when I use
Server.Transfer("page1.htm") to transfer to a different page?
Server.Transfer only works
with .aspx pages
You can't use Transfer method
with HTML pages
46 . How to detect the User's culture?
VB.NET
Dim sLang As String
sLang =
Request.UserLanguages(0)
Response.Write(sLang)
C#
string sLang ;
sLang =
Request.UserLanguages[0];
Response.Write (sLang);
47 . What is the difference between CurrentCulture
property and the CurrentUICulture property?
# CurrentCulture property :
affects how the .NET Framework handles dates, currencies, sorting and
formatting issues
# CurrentUICulture property :
determines which satellite assembly is used when loading resources
48 . Can I read the hard disk serial # of the client
computer using ASP.NET?
No. Such information is not
passed to the server with a http request.
49 . What is xxx(src As Object, e As EventArgs)?
xxx is an event handler
src is the object that fires
the event
e is an event argument object
that contains more information about the event
An event handler is used when
one object wants to be notified when an event happens in another object
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Dot Net - C#.Net””””””””””””””””””””
1 . Does C# support multiple-inheritance?
No.
2 . Who is a protected class-level variable available
to?
It is available to any
sub-class (a class inheriting this class).
3 . Are private class-level variables inherited?
Yes, but they are not
accessible. Although they are not
visible or accessible via the class interface, they are inherited.
4 . Describe the accessibility modifier “protected
internal”.
It is available to classes
that are within the same assembly and derived from the specified base class.
5 . What’s the top .NET class that everything is
derived from?
System.Object.
6 . What does the term immutable mean?
The data value may not be
changed. Note: The variable value may be
changed, but the original immutable data value was discarded and a new data
value was created in memory.
7 . What’s the difference between System.String and
System.Text.StringBuilder classes?
System.String is
immutable. System.StringBuilder was
designed with the purpose of having a mutable string where a variety of
operations can be performed.
8 . What’s the advantage of using System.Text.StringBuilder over System.String?
StringBuilder is more
efficient in cases where there is a large amount of string manipulation. Strings are immutable, so each time a string
is changed, a new instance in memory is created.
9 . Can you store multiple data types in System.Array?
No.
10 . What’s the difference between the
System.Array.CopyTo() and System.Array.Clone()?
The Clone() method returns a
new array (a shallow copy) object containing all the elements in the original
array. The CopyTo() method copies the
elements into another existing array.
Both perform a shallow copy. A
shallow copy means the contents (each array element) contains references to the
same object as the elements in the original array. A deep copy (which neither of these methods
performs) would create a new instance of each element's object, resulting in a
different, yet identacle object.
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Dot Net - Asp.Net 2.0 Interview Questions
1 . What are the new Data Controls in Asp.net 2.0?
Data access in ASP.NET 2.0
can be accomplished completely declaratively (no code) using the new data-bound
and data source controls. There are new data source controls to represent
different data backends such as SQL database, business objects, and XML, and
there are new data-bound controls for rendering common UI for data, such as
gridview, detailsview, and formview.
2 . What are the new Navigation Controls in Asp.net
2.0?
The navigation controls
provide common UI for navigating between pages in your site, such as treeview,
menu, and sitemappath. These controls use the site navigation service in
ASP.NET 2.0 to retrieve the custom structure you have defined for your site.
3 . What are the new Login Controlsin Asp.net 2.0?
The new login controls
provide the building blocks to add authentication and authorization-based UI to
your site, such as login forms, create user forms, password retrieval, and
custom UI for logged in users or roles. These controls use the built-in
membership and role services in ASP.NET 2.0 to interact with the user and role
information defined for your site.
4 . What are the new Web Part Controls in Asp.net 2.0
?
Web parts are an exciting new
family of controls that enable you to add rich, personalized content and layout
to your site, as well as the ability to edit that content and layout directly
from your application pages. These controls rely on the personalization
services in ASP.NET 2.0 to provide a unique experience for each user in your
application.
5 . What are Master Pages?
This feature provides the
ability to define common structure and interface elements for your site, such
as a page header, footer, or navigation bar, in a common location called a
"master page", to be shared by many pages in your site. In one simple
place you can control the look, feel, and much of functionality for an entire
Web site. This improves the maintainability of your site and avoids unnecessary
duplication of code for shared site structure or behavior.
6 . What are Themes and Skins in 2.0, explain usgae
scenario?
The themes and skins features
in ASP.NET 2.0 allow for easy customization of your site's look-and-feel. You
can define style information in a common location called a "theme",
and apply that style information globally to pages or controls in your site.
Like Master Pages, this improves the maintainability of your site and avoid
unnecessary duplication of code for shared styles.
7 . What is a profile object, why is it used?
Using the new personalization
services in ASP.NET 2.0 you can easily create customized experiences within Web
applications. The Profile object enables developers to easily build
strongly-typed, sticky data stores for user accounts and build highly
customized, relationship based experiences. At the same time, a developer can
leverage Web Parts and the personalization service to enable Web site visitors
to completely control the layout and behavior of the site, with the knowledge
that the site is completely customized for them. Personalizaton scenarios are
now easier to build than ever before and require significantly less code and
effort to implement.
8 . What is Configuration API?
ASP.NET 2.0 contains new
configuration management APIs, enabling users to programmatically build
programs or scripts that create, read, and update Web.config and machine.config
configuration files.
9 . What is MMC Admin Tool?
ASP.NET 2.0 provides a new
comprehensive admin tool that plugs into the existing IIS Administration MMC,
enabling an administrator to graphically read or change common settings within
our XML configuration files.
10 . Explain the use of Pre-compilation Tool?
ASP.NET 2.0 delivers a new
application deployment utility that enables both developers and administrators
to precompile a dynamic ASP.NET application prior to deployment. This
precompilation automatically identifies any compilation issues anywhere within
the site, as well as enables ASP.NET applications to be deployed without any
source being stored on the server (one can optionally remove the content of
.aspx files as part of the compile phase), further protecting your intellectual
property.
11 . How is application management and maintenance
improved in Asp.net 2.0?
ASP.NET 2.0 also provides new
health-monitoring support to enable administrators to be automatically notified
when an application on a server starts to experience problems. New tracing
features will enable administrators to capture run-time and request data from a
production server to better diagnose issues. ASP.NET 2.0 is delivering features
that will enable developers and administrators to simplify the day-to-day
management and maintenance of their Web applications.
12 . What are Provider-driven Application Services?
explain in detail?
ASP.NET 2.0 now includes
built-in support for membership (user name/password credential storage) and
role management services out of the box. The new personalization service
enables quick storage/retrieval of user settings and preferences, facilitating
rich customization with minimal code. The new site navigation system enables
developers to quickly build link structures consistently across a site. As all
of these services are provider-driven, they can be easily swapped out and replaced
with your own custom implementation. With this extensibility option, you have
complete control over the data store and schema that drives these rich
application services.
13 . Explain Server Control Extensibility with
reference to Asp.net 2.0 ?
ASP.NET 2.0 includes improved
support for control extensibility, such as more base classes that encapsulate
common behaviors, improved designer support, more APIs for interacting with
client-side script, metadata-driven support for new features like themes and accessibility
verification, better state management, and more.
14 . What are the Data Source Controls?
Data access in ASP.NET 2.0 is
now performed declaratively using data source controls on a page. In this
model, support for new data backend storage providers can be easily added by
implementing custom data source controls. Additionally, the SqlDataSource
control that ships in the box has built-in support for any ADO.NET managed
provider that implements the new provider factory model in ADO.NET.
15 . What are Compilation Build Providers?
Dynamic compilation in
ASP.NET 2.0 is now handled by extensible compilation build providers, which
associate a particular file extension with a handler that knows how to compile
that extension dynamically at runtime. For example, .resx files can be
dynamically compiled to resources, .wsdl files to web service proxies, and .xsd
files to typed DataSet objects. In addition to the built-in support, it is easy
to add support for additional extensions by implementing a custom build provider
and registering it in Web.config.
16 . What is Expression Builders, why would you use
it?
ASP.NET 2.0 introduces a
declarative new syntax for referencing code to substitute values into the page,
called Expression Builders. ASP.NET 2.0 includes expression builders for
referencing string resources for localization, connection strings, application
settings, and profile values. You can also write your own expression builders
to create your own custom syntax to substitute values in a page rendering.
17 . Is ASP.NET 64-Bit enabled? how?
ASP.NET 2.0 is now 64-bit
enabled, meaning it can take advantage of the full memory address space of new
64-bit processors and servers. Developers can simply copy existing 32-bit
ASP.NET applications onto a 64-bit ASP.NET 2.0 server and have them
automatically be JIT compiled and executed as native 64-bit applications (no
source code changes or manual re-compile are required).
18 . Explain how Caching in Asp.net 2.0 is different
from Caching in Asp.net 1.1?
ASP.NET 2.0 also now includes
automatic database server cache invalidation. This powerful and easy-to-use
feature allows developers to aggressively output cache database-driven page and
partial page content within a site and have ASP.NET automatically invalidate
these cache entries and refresh the content whenever the back-end database
changes. Developers can now safely cache time-critical content for long periods
without worrying about serving visitors stale data.
19 . Can we bind data to a server control without
writing code in .NET?
Yes, that is possible.
ASP.NET 2.0 has the feature of declarative solution for data binding which
requires no code at all for the most common data scenarios, such as:
* Selecting and displaying
* Data Sorting
* Paging and Caching
* Data Updating
* Inserting and Deleting Data
20 . How to use Masterpages and Contentpages in
ASP.NET 2.0? What is a Masterpage? What is a ContentPage? How to setup
master-content pages in ASP.NET 2.0?
A Master Page is the mother
of the page and the content page is the baby! There may be many babies of the
mother. A master page may have plenty of content pages within it. There also
may be a master page within a master page, which is called a nested master
page.
So whats a master page in
ASP.NET 2.0? A Master Page is a page that contains markup and controls that are
shared across multiple pages in your site. For example, if required that all
pages should have the same header and footer banners or the common navigation
menu, the Master page can be written once, and all the content pages can access
the common master page. The content pages inherit the tags inside the master
page.
Next question is how to
define a master page. The answer is...
To define a Master Page, it
may be written like a normal page. Master Pages can contain markup, controls,
or code, or any combination of these tags. The Content pages are rendered in a
master page control called as ContentPlaceHolder control. A ContentPlaceHolder
defines a region of the master page rendering that can be exchanged with
content from a page associated to the master. A ContentPlaceHolder can also
contain default content, when in case the derive page does not need to override
this content. Below is the markup of how to use a Contentplaceholder.
<asp:contentplaceholder
id="ContentPlaceHolderInterviewQuestions"
runat="server"/>
<asp:contentplaceholder
id="ContentPlaceHolderInterviewQuestions"
runat="server">
<h3>Welcome to the .NET
Interview Questions website!</h3>
</asp:contentplaceholder>
A master page has the extension
.master, unlike a normal web form that has the extenstion .aspx. A page may
derive from a Master Page by defining a MasterPageFile attribute on its Page
directive. Below is the markup of a content page.
<%@ Page
MasterPageFile="Masterpage.master" %>
<asp:content
id="Content1"
contentplaceholderid="ContentPlaceHolderInterviewQuestions"
runat="server">
Here goes contents of
ContentPlaceHolderInterviewQuestions </asp:content>
</asp:content>
So how does Content page
access a master page? It is also possible for a Content Page to
programmatically access a Master Page. A ContentPage may create a
strongly-typed reference to the Master Page using the <%@ MasterType %>
directive, which specifies the virtual path to the masterpage as below...
<%@ MasterType VirtualPath="Masterpage.master"
%>
The Content Page may then
reference the Master Page using the Master property of the Page class:
Master.FooterText =
"Some text on the footer of .NET Interview Questions page";
Label lb1 =
Master.FindControl("label2");
As with the example above,
FooterText is a public property exposed on the Master Page, whereas label2 is a
server side control on the Master Page.
Note that the FindControl
method is a very useful and a very important method, that may be used for
finding a control in a content page from a master page and vice versa.
21 . What is a nested Masterpage in ASP.NET 2.0? Can
there be a master page inside a masterpage?
When a master page is placed
inside the contentplaceholder of a masterpage, then the masterpage is said to
be nested. In other words, there is one parent masterpage, and the child
masterpage is inside the contentplaceholder of the parent masterpage.
22 . What is a SiteMapPath control in ASP.NET 2.0?
An asp:SiteMapPath control is
a Navigation Control that comes along with the ASP.NET 2.0 framework. The
sitemappath control consists site link's data in XML format. The emergence of
the Sitemappath control in ASP.NET 2.0 has totally eliminated the clumsy code
used in bread crumbs by veteran web developers in Classic ASP and ASP.NET 1.1.
These bread crumbs were comparatively tougher to maintain.
Now say you need to maintain
a Sitemap of a Site having the following links...
Home Products Medicines Soaps
Alcohol Support Phone Support Email Support Contact Us
Instead of hard coding these
links inside your code, all this information may be maintained in an XML based
Web.sitemap file which can be bind to an asp:SiteMapPath control, and this
would display like a website breadcrumb. Easier than before!
The SiteMapPath control's
SiteMapProvider property is used to set the site's sitemap provider. This
sitemap provider is another control called asp:XmlDataSource control. This
needs to be registered in the web.config file. If the SiteMapProvider property
is not specified, then the default SiteMap Provider information is picked up
from the web.config file.
Note:The other two navigation
controls in ASP.NET 2 are the Menu control and the TreeView control.
The XmlDataSource control
loads an XML file that is specified using the DataFile property. This control
inherits from the HierarchicalDataSourceControl class.
Example XML below:
<asp:SiteMapPath
ID="smm1" runat="server"
SiteMapProvider="xds1"></asp:SiteMapPath>
<asp:XmlDataSource
ID="xds1" DataFile="somefile.xml"
runat="server"></asp:XmlDataSource>
If DataFile is not used in
the XmlDataSource, the siteMapFile property can be set in the web.config.
In order to specify XML Data
Source in web.config, see below:
<configuration>
<system.web>
<siteMap
defaultProvider="XmlSiteMapProvider" enabled="true">
<providers>
<clear/>
<add name="XmlSiteMapProvider"
<description="Default SiteMap
provider"
<type="System.Web.XmlSiteMapProvider"
<siteMapFile="~/Web.sitemap"
</>
</providers>
</siteMap>
</system.web>
</configuration>
23 . 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.
24 . 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.
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.
<asp:ImageMap
ID="ImageMap1" Runat="Server"
ImageUrl="Photo.gif"
OnClick="SomeEvent"
AlternateText="Click
Here"
HotSpotMode="Navigate">
<asp:PolygonHotSpot
AlternateText="Click
Here Too!"
Coordinates="100,150,
250,350, 210,290, 90,350, 60,240"
NavigateUrl="http://www.asp.net"
Target="_blank"/>
</asp:ImageMap>
25 . 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.
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Dot Net - ADO.Net Interview Questions
1 . What is ADO.NET?
ADO.NET is a part of the
Microsoft .NET Framework. This framework provides the set of classes that deal
with data communication between various layers of the software architecture and
the database. It provides a continious access to different data source types
such as SQL Server versions 7, 2000, 2005. It also provides connectivity
options to data sources through OLE DB and XML. Connectivity may be established
with other databases like Oracle, MySQL etc. as well.
ADO.NET has the ability to
separate data access mechanisms, data manipulation mechanisms and data
connectivity mechanisms.
ADO.NET introduces along with
it the disconnected architecture. In a disconncted architecture, data may be
stored in a DataSet. It contains providers for connecting to databases,
commands for execution and retrieval of results.
The classes for ADO.NET are
stored in the DLL System.Data.dll.
2 . What is a connection object in ADO.NET? How to
connect to a database in .Net?
A Connection object in
ADO.NET is used to establish a connection between a program (the program may be
a windows page, a web page, a windows service, a web service etc.) and the
database. The connection is open just long enough to get or update data. By
quickly opening, then closing a connection, the server resources are used as
little as possible. See code below on how to open a connection between UI and
database...
'Code below in VB.NET ...
Dim objectConn as
SqlClient.SqlConnection
Dim strConn as String
Try
'First, create a connection
object
objectConn=New
SqlClient.SqlConnection()
'Next, build the Connection
String
strConn &="Data
Source=(local
strConn &="Initial
Catalog=DatabaseName;"
strConn &= "User
ID=admin;"
strConn &=
"Password=;"
'Note here that the
connection string may also be passed as a parameter
'to the connection string
object during instantiation
objectConn.ConnectionString =
strConn
objectConn.Open() 'Open the
Connection
'The connection is now open
'Write your vb.net code here
for operations on the database
objectConn.Close()
Catch Ex As Exception
MessageBox.Show(Ex.Message)
End Try
3 . What are Connection Strings
A connection string has a
group of semi-colon-separated attributes. Every .Net Data Provider connection
string looks different, depending on the type of .NET Data Provider you need to
use and which attributes are set for each different type of database system. An
example, the connection string below is an example of what you use to connect
to a local SQL Server. See that every parameter is separated by a semicolon.
Data Source=(local);Initial
Catalog=Northwind;User ID=sa;Password=;
The connection string shown
below is an example of how to connect to a Microsoft Access 2000 database using
the OleDbConnection object in System.Data.OleDb.
Provider=Microsoft.Jet.OleDb.4.0;Data
Source=C:\Northwind.mdb
Parameters in a Connection
String - The parameters depend on the data provider is being used.
Server - The name of the SQL
Server to which connection has to be established through ADO.NET. This is the
name of the system that is running SQL server. We may use "local" or
"localhost" for local computer. In case we are using named instances
of SQL server, then the parameter would contain the computer name, followed by
a backslash, followed by a named instance of the SQL server.
Database - The name of the
database to which connection is to be established.
User ID - A user ID
configured in the SQL Server by the SQL Server administrator.
Password - As the attribute
name suggests, this is the password associated with the user id.
Note that connection string
may also contain the Windows NT account security settings. This is done by
passing the paramater "integrated security=true".
4 . What is a command object in ADO.NET. How to use a
command object in .NET?
ADO.NET Command Object - The
Command object is similar to the old ADO
'Code below in VB.NET ...
Dim ObjCom as
SqlClient.SqlCommand
ObjCom.SqlConnection(strCon)
ObjCom.Connection.Open()
ObjCom.CommandText =
"Select * from tblSample"
ObjCom.ExecuteNonQuery()
SqlCommand objects are not
used much when we use datasets and data adapters. Following are some properties
of the SqlCommand class...
Connection Property - This
property contains data about the connection string. It must be set on the
SqlCommand object before it is executed. For the command to execute properly,
the connection must be open at the time of execution.
CommandText Property - This
property specifies the SQL string or the Stored Procedure.
objCom.CommandText =
"Insert into Employees (empid, empname) values ('EMI0334','Mandy')"
Paramaters Collection - If we
want to update values in the Employees table above, but we do not know the
values at design time, we make use of placeholders. These are variables
prefixed with "@" symbol. Our code will look like this...
objCom.CommandText =
"Insert into Employees (empid, empname) values (@empid, @empname)
Next, we have to create
parameters that will be used to insert values into the placeholders. For this,
we need to add parameters to the parameters collection of the SqlCommand
object. This is done so that the values added through the parameters collection
& placeholders get i ncluded in the SQL statement. Here, parameters mean
the parameters to be passed to the SQL statement/Stored Procedures, not the
method's parameters.
In order to add parameters to
the SqlCommand object, we write the following code...
objCom.CommandText =
"Insert into Employees (empid, empname) values (@empid, @empname)"
objCom.Parameters.Add("@empID",
txtempid.text)
objCom.Parameters.Add("@empname",
txtempname.text)
ExecuteNonQuery Method - Once
the connection is open, we run the query in the SqlCommand object using the
ExecuteNonQuery method. This is very simple as shown below...
objConnection.Open()
objCom.ExecuteNonQuery()
objConnection.Close()
5 . What is SelectCommand in ADO.NET?
Select Command Property -
This property is used to hold the SQL command that is used to retrieve data from
the data source. The CommandText and Connection are properties of the Select
Command propety. CommandType is also a property of Select Command. See example
below...
Dim da as new SqlDataAdapter
da.SelectCommand = New
SqlCommand( )
With da.SelectCommand
.Connection = objConnection
.CommandText = "select *
from employees"
End With
6 . What is a SqlCommandBuilder in ADO.NET
SqlCommandBuilder class in
ADO.NET provides the feature of reflecting the changes made to a DataSet or an
instance of the SQL server data. When an instance of the SqlCommandBuilder
class is created, it automatically generates Transact-SQL statements for the
single table updates that occur. The object of the SqlCommandBuilder acts as a
listener for RowUpdating events, whenever the DataAdapter property is set.
The SqlCommandBuilder object
automatically generates the values contained within the SqlDataAdapter's
InsertCommand, UpdateCommand and DeleteCommand properties based on the initial
SelectCommand. The advantage here is that you will not need to write SqlCommand
& SqlParameter Types explicitly.
Basically the command builder
object builds these objects on the fly. The command builder object actually
reads the metadata of the method called. After the builder object reads the
underlying schema of the adapter's method, it autogenerates an underlying
insert, update & delete command object. See code example below...
//Code below in C#...
DataSet ds = new DataSet();
SqlConnection cn = new
SqlConnection("strSomeConnectionString");
//Autogenerate Insert, Update
& Delete commands
SqlDataAdapter da = new
SqlDataAdapter("Select from t_Something", cn);
SqlCommandBuilder scb = new
SqlCommand(da);
//Fill the dataset
da.Fill(ds,"t_Something");
7 . What is a DataView in ADO.NET?
DataView - Just like we have
Views in SQL (in our backend), we have DataView object in ADO.NET. A dataview
object represents bindable, customized view of a DataTable object. Operations
like Sorting, Filtering, Searching, Editing and Navigation may be performed on
a DataView object. In scenarios like retrieval of a subset of data from a
Datatable, we may make use of DataViews to get this data. Note that the
DefaultView property of a DataTable returns the Default data view for the
DataTable. In case a custom view of a DataTable has to be created on a
DataView, then the RowFilter property of the DataView is set to the
DefaultView.
A dataview may also be used
to sort data that resides in it in ascending or descending order. Below is code
on how to sort data in a dataview in ascending or descending order...
DataView objdv = new
DataView();
objdv.Sort("ColumnName
Asc|Desc");
8 . What is DataRelation object in ADO.NET? How to use
a DataRelation between two columns in ADO.NET?
In order to set the
relationship between two or more than two columns, ADO.NET provides the
DataRelation class. When a DataRelation object is created, it assists to
enforce some constraints on the relationships between columns. The constraint
may be like a Unique constraint that ensures that a column will have no
duplicate value in the table. A Foreign Key constraint may be used to enforce
Referential Integrity. The Unique property may be set by setting the Unique
property of a DataColumn to True. This may also be done by adding an instance
of the UniqueConstraint class to the DataRelation object. As a part of the
foreign key constraint, we may specify referential integrity rules that are
applied at 3 places
1) When a parent record is
updated
2) When a parent record is
deleted
3) When a change is rejected
or accepted.
A DataRelation object permits
to establish a parent-child relationship between two or more tables inside a
DataSet object. The easiest way to create a DataRelation between two tables in
a DataSet is to setup a primary key - foreign key relationship between the
columns of a table.
See code example below, where
a DataRelation has been setup between the Employee table and the Salary
table...
'Code Below in VB.NET
Dim Conn
Dim da As SqlDataAdapter
Dim ds As DataSet
Dim RowParent As DataRow
Dim RowChild As DataRow
SqlConnection(ConfigurationSettings.Appsettings("SomeConnectionStringWrittenInWeb.Config"))
da = New
SqlDataAdapter("SELECT * FROM Employees", Conn
ds = New DataSet()
Try
Conn.Open()
da.Fill( ds,"Employees")
da.SelectCommand = New
SqlCommand("SELECT * FROM Salary", Conn
da.Fill(ds, "Salary")
Catch ex As SqlException
Response.Write(ex.ToString())
Finally
Conn.Dispose()
End Try
'Next, Let us create a Data
Relationship
ds.Relations.Add("Employee_Salary",
ds.Tables("Employees").Columns("EmployeeID"), _
ds.Tables("Salary").Columns("EmployeeID"))
'Display the Employee and
Child Salary in the Form
'Say we have a Label in the
form
For each RowParent in
ds.Tables("Employees").Rows
lblRelation.Text &=
RowParent("Emp_Name")
For each RowChild in
RowParent.GetChildRows("Employee_Salary")
lblRelation.Text &=
"<br/>" & RowChild("Sal_Amount")
Next
Next
9 . What is Diffgram in ADO.NET? When do we use
Diffgram?
A DiffGram is an XML format.
It is used to identify current and original versions of data elements. A
DataSet may use a DiffGram format to load and persist the contents, and further
to serialize its contents for porting across a network connection. Whenever a
DataSet is written as a DiffGram, the DataSet populates the DiffGram with all
the important information to accurately recreate the contents. Note that schema
of the DataSet is not recreated. This includes column values from both the
Current and the Original row versions, row error information, and row order.
10 . What is a Typed Dataset
in ADO.NET? Why do we use a Typed DataSet? What is the difference between a
Typed and an UnTyped DataSet?
Typed DataSet - When a
created DataSet derives from the DataSet class, that applies the information contained
in the XSD to create a Typed class, this DataSet is said to be a Typed Dataset.
Information from the schema whic comprises the tables, columns, and rows is
created and compiled to a new DataSet derived from the XSD. The Typed DataSet
class features all functionality of the DataSet class. This may be used with
methods that take an instance of the DataSet class as a parameter.
Note that an UnTyped DataSet
does not have any schema. It is exposed simply as a mere collection.
How to create a Typed DataSet?
-
Write click your project in
the Solution Explorer.
Click Add New Item.
Select DataSet.
This adds a new XSD to the
project. The schema created may be viewed as an XML. When this xsd file is
compiled, two files are created by Visual Studio. The first file that contains
the .vb or .cs extension contains the information about the proxy class. This
class contains methods & properties that are required to access the
database data. The second file has an extension xsx and this contains
information about the layout of the XSD.
11 . How to run a stored procedure from .NET code?
Use the Command object and
its ExecuteNonQuery method to run a DDL or DCL statement of SQL. First, create
a connection object and a command object, and configure these objects for the
statement you wish to execute. Open the database connection. Call
ExecuteNonQuery on the command. Close the connection.
Example
Suppose we have to insert
FirstName into a table t_Employees. Our Store procedure is:
Create Procedure
dbo.InsertFirstName
(
@FirstName varchar(30)
)
as
Insert Into t_Employees
values (@FirstName)
VB.NET code below, to pass
FirstName to this Stored Procedure
Dim cmRunProc as New
SqlCommand("dbo.InsertFirstName", objCon)
cmRunProc.CommandType =
CommandType.StoredProcedure
cmRunProc.Parameters.Add("@FirstName",
txtFirstName.Text)
objCon.Open()
cmdRunProc.ExecuteNonQuery()
objCon.Close()
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------------
Previous Technology: ADO
Latest Technology: ADO
Database Providers:
-----------------------
1) Odbc [System.Data.Odbc]
2) OleDb [System.Data.OleDb]
3) Sql [System.Data.SqlClient]
4) Oracle [System.Data.OracleClient]
Components of ADO
------------------------------
1) Connection
2) DataAdapter
3) CommandBuilder
4) DataSet
i) DataTable
ii) DataColums
iii) DataRow
5) Command
6) DataReader
1) Connection
- OdbcConnection
- OleDbConnection
- SqlConnection
- OracleConnection
OdbcConnection cn=new
OdbcConnection("dsn=ajay;uid=xxx;pwd=xxx");
OleDbConnection cn=new
OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data
Source=D:\Scott.mdb;Persist Security Info=False");
SqlConnection cn=new
SqlConnection("Data Source=.\SQLEXPRESS;Initial Catalog=scott;Integrated
Security=true");
OracleConnection cn=new
OracleConnection("user id=scott;password=tiger");
2) DataAdapter
--OdbcDataAdapter
--OleDbDataAdapter
--SqlDataAdapter
--OracleDataAdapter
SqlDataAdapter ada=new
SqlDataAdapter("select * from dept",cn);
3) CommandBuilder
--OdbcCommandBuilder
--OleDbCommandBuilder
--SqlCommandBuilder
--OracleCommandBuilder
SqlCommandBuilder cmb=new
SqlCommandBuilder(ada);
4) DataSet
DataSet ds=new DataSet();
ada.fill(ds,"Dept");
ada.update(ds,"Dept");
5) Command
--OdbcCommand
--OleDbCommand
--SqlCommand
--OracleCommand
Select- SingleValueQuery -- ExecuteScalar()
- MultiValueQuery --ExecuteReader()
Insert ---
Update
-----> ExecuteNonQuery();
Delete
---
SqlCommand cmd=new
SqlCommand("insert into dept values(10,'Sales','Lucknow
cn.open();
cmd.ExecuteNonQuery();
cn.close();
SqlCommand cmd=new
SqlCommand("updae dept set dname='Sales',loc='Kanpur
cn.open();
cmd.ExecuteNonQuery();
cn.close();
SqlCommand cmd=new
SqlCommand("delete from dept where deptno=20",cn);
cn.open();
cmd.ExecuteNonQuery();
cn.close();
SqlCommand cmd=new
SqlCommand("select max(deptno) from dept",cn);
cn.open();
int
mdno=Convert.ToInt32(cmd.ExecuteScalar());
cn.close();
6) DataReader
--OdbcDataReader
--OleDbDataReader
--SqlDataReader
--OracleDataReader
SqlCommand cmd=new
SqlCommand("select deptno,dname from dept",cn);
cn.open();
SqlDataReader rd=cmd.ExecuteReader(CommandBehaviour.CloseConnection);
while(rd.Read())
{
cmbDept.items.add(String.format("{0} ({1})",rd[1],rd[0]));
}
rd.close();
