Here I am posting the interview questions
whatever i have faced in my interviews
I have searched for
so many websites and gathered information from my friends to answer the
questions perfectly.
i think these questions are very helpful for
the people who are trying to get the job on .NET
The most common question for experience
persons is
Why would you like to change the company?
1) I am looking for a more challenging career
in a firm with a larger employee base such as yours.
2) Keeping in mind my career goals, the time
has come for me to move onto the next rung of
the ladder and make a mark for myself. This
can be achieved in a company like this.
3) It is just a career move to enhance my
knowledge in my own area of interest.
After completion of this question only
interview will go for further questions
Difference between stored procedure and function
1) Procedure can return zero or n values
whereas function can return one value which is mandatory.
2) Procedures can have input, output parameters for it whereas functions can
have only input parameters.
3) Procedure allows select as well as DML statement in it whereas function
allows only select statement in it.
4) Functions can be called from procedure whereas procedures cannot be called
from function.
5) Exception can be handled by try-catch block in a procedure whereas try-catch
block cannot be used in a function.
6) We can go for transaction management in procedure whereas we can't go in
function.
7) Procedures cannot be utilized in a select statement whereas function can be
embedded in a select statement.
Difference between Abstract and Interface
Abstract Class:
-Abstract class provides a set of rules to implement next
class
-Rules will be provided through abstract methods
-Abstract method does not contain any definition
-While inheriting abstract class all abstract methods must be override
-If a class contains at least one abstract method then it must be declared as
an “Abstract Class”
-Abstract classes cannot be instantiated (i.e. we cannot create objects), but a
reference can be created
-Reference depends on child class object’s memory
-Abstract classes are also called as “Partial abstract classes”
-Partial abstract class may contain functions with body and functions without
body
-If a class contains all functions without body then it is called as “Fully
Abstract Class” (Interface)
Interface:
-If a class contains all abstract methods then that class
is known as “Interface”
-Interfaces support like multiple inheritance
-In interface all methods r public abstract by default
-Interfaces r implementable
-Interfaces can be instantiated, but a reference cannot be created
Index types in SQL Server
Clustered Index
Only 1 allowed per
table physically rearranges the data in the table to confirm to the index
constraints for use on columns that are frequently searched for ranges of data
for use on columns with low selectivity.
Non-Clustered Index
Up
to 249 allowed per table creates a separate list of key values with pointers to
the location of the data in the data pages For use on columns that are searched
for single values
A clustered index
is a special type of index that reorders the way records in the table are
physically stored. Therefore table can have only one clustered index. The leaf
nodes of a clustered index contain the data pages. A non-clustered index is a
special type of index in which the logical order of the index does not match
the physical stored order of the rows on disk. The leaf node of a non-clustered
index does not consist of the data pages. Instead, the leaf nodes contain index
rows.
Included Column Index
(New in SQL Server 2005)
In
SQL Server 2005, the functionality of non-clustered indexes is extended by
adding non-key columns to the leaf level of the non-clustered index. Non-key columns
can help to create cover indexes. By including non-key columns, you can create
non-clustered indexes that cover more queries. The Database Engine does not
consider non-key columns when calculating the number of index key columns or
index key size. Non-key columns can be included in non-clustered index to avoid
exceeding the current index size limitations of a maximum of 16 key columns and
a maximum index key size of 900 bytes. Another advantage is that using non-key
column in index we can have index data types not allowed as index key columns
generally.
In
following example column Filename is varchar(400), which will increase the size
of the index key bigger than it is allowed. If we still want to include in our
cover index to gain performance we can do it by using the Keyword INCLUDE.
USE AdventureWorks
GO
CREATE INDEX IX_Document_Title
ON Production.Document
(Title, Revision)
INCLUDE (FileName)
Non-key columns can
be included only in non-clustered indexes. Columns can’t be defined in both the
key column and they INCLUDE list. Column names can’t be repeated in the INCLUDE
list. Non-key columns can be dropped from a table only after the non-key index
is dropped first. For Included Column Index to exist there must be at least one
key column defined with a maximum of 16 key columns and 1023 included columns.
Avoid adding
unnecessary columns. Adding too many index columns, key or non-key as they will
affect negatively on performance. Fewer index rows will fit on a page. This
could create I/O increases and reduced cache efficiency. More disk space will
be required to store the index. Index maintenance may increase the time that it
takes to perform modifications, inserts, updates, or deletes, to the underlying
table or indexed view.
Another example to test:
Create following Index on Database
AdventureWorks in SQL SERVER 2005
USE AdventureWorks
GO
CREATE NONCLUSTERED INDEX IX_Address_PostalCode
ON Person.Address
(PostalCode)
INCLUDE (AddressLine1,
AddressLine2, City,
StateProvinceID)
GO
Test the performance of following query before and after creating Index. The
performance improvement is significant.
SELECT AddressLine1, AddressLine2,
City, StateProvinceID,
PostalCode
FROM Person.Address
WHERE PostalCode
BETWEEN '98000'
AND '99999';
GO
Interview questions
What are differences between Array list and
Hash table?
Ans:
1)
Hash table store data as name, value pair. While in array only value is store.
2) To access value from hash table, you need
to pass name. While in array, to access value, you need to pass index number.
3) you can store different type of data in
hash table, say int, string etc. while in array you can store only similar type
of data.
What are differences between
system.stringbuilder and system.string?
The main difference is system.string is immutable
and system.stringbuilder is a mutable. Append keyword is used in string builder
but not in system.string.
Immutable means once we created we cannot
modified. Suppose if we want give new value to old value simply it will
discarded the old value and it will create new instance in memory to hold the
new value.
What are the differences between
Application object and session object?
Ans: The session object is used to maintain the session of each user.
If one user enter in to the application then they get session id if he leaves
from the application then the session id is deleted. If they again enter in to
the application they get different session id.
But for application object the id is maintained for whole application.
What are the different types of indexes?
Ans:
Two types of indexes are there one is clustered index and
non-clustered index
How many types of memories are there in
.net?
Ans:
Two types of memories are there in .net stack memory and
heap memory
Is it possible to set the session out time
manually?
Ans:
Yes we can set the session out time manually in
web.config.
What are differences between function and stored procedure?
Ans:
1) Function returns only one value but
procedure returns one or more than one value.
2) Function can be utilized in select
statements but that is not possible in procedure.
3) Procedure can have an input and output
parameters but function has only input parameters only.
4) Exceptions can be handled by try catch
block in procedures but that is not possible in function.
What are the differences between Abstract
and interface?
Ans:
1) Abstract cannot be instantiated but we can
inherit. Interface it cannot be inherit it can be instantiate
2) Interface contain only declarations no
definitions. Abstract contain declarations and definitions.
3) The class which contains only abstract
methods is interface class. A class which contains abstract method is called
abstract class
4) Public is default access specifier for
interface we don’t have a chance to declare other specifiers. In abstract we
have chance to declare with any access specifier
Can you Explain Page lifecycle in .net?
Can you Explain .NET architecture in .net?
What is the difference between primary key
and unique key with not null?
Ans:
There is no difference between primary key and unique key
with not null.
What is boxing and unboxing concepts in
.net?
Ans:
Boxing
is a process of converting value type into reference type
Unboxing is a process of converting reference
type to value type.
What are the differences between value type
and reference type?
Ans:
Value
type contain variable and reference type are not containing value directly in
its memory.
Memory is allocated in managed heap in
reference type and in value type memory allocated in stack. Reference type
ex-class value type-struct, enumeration
Is it possible to host the website from
desktop?
Ans:
Yes
Why we go for page rendering in Asp.Net
Page life cycle?
Ans:
Browser understands an only html control that’s why in
page rendering we will convert the aspx controls into html controls.
Write a sample query for self join?
Ans:
Select e1.ename, e2.empid from emp e1, emp e2 where
e1.empid=e2.mgrid;
Can we change the index of primary key on
table?
Ans:
No
How to change the name of the table or
stored procedure in sql?
Ans:
sp_rename oldtablename newtablename
For changing the column name
Sp_rename
‘tablename.[Oldcolumnname]’,’newcolumnname’,’Column’
Ex:sp_rename
‘tblemp.first’,’namechange’,’Column’
How to find out which index is defined on
table?
Ans:
sp_helpindex tablename
Can you write the program to find the
length of string without using library function?
Ans:
for (int i=0; str[i]!=”\n”; i++)
{
Count++;
}
What is the difference between
scope_identity() and current_identity()?
Ans:
Scope_identity and current _identity both are similar and
it will return the last identity value generated in the table.
Scope_Identity will return the identity value
in table that is currently in scope
What are difference between GET and POST
Methods?
Ans:
GET Method ():
1) Data is appended to the URL.
2) Data is not secret.
3) It is a single call system
4) Maximum data that can be sent is 256.
5) Data transmission is faster
6) this is the default method for many browsers
POST Method
():
1) Data is not appended to the URL.
2) Data is Secret
3) it is a two call system.
4) There is no Limit on the amount of data. That is characters any amount of
data can be sent.
5) Data transmission is comparatively slow.
6) No default and should be explicitly specified.
What are difference between truncate and
delete?
Ans:
1)
Delete keep the lock over each row where Truncate keeps the lock on table not
on all the row.
2) Counter of the Identity column is reset in Truncate where it is not reset in
Delete.
3) Trigger is not fired in Truncate where as trigger is fired in Delete.
4) In TRUNCATE we cannot rollback.
5) In DELETE we can rollback
What is the difference Grid View and
between Data Grid (Windows)?
Ans:
1) GridView Control Enables you to add
sorting, paging and editing capabilities without writing any code.
2)GridView Control Automatically Supports paging by setting the ‘PagerSetting’
Property.The Page Setting Property supports four Modles
a. Numeric(by default)
b. Next Previous
c. NumericFirstLast
d. Next PreviousLast
3)It is Used in asp.net
4)GridView Supports RowUpdating and RowUpdated Events.
5)GidView is Capable of Pre-Operations and Post-Operations.
6)GridView Has EditTemplates for this control
7)It has AutoFormat
DataGrid(Windows)
1)DataGid Control raises single Event for operations
2)DataGird Supports the SortCommand Events that occur when a column is Soted.
3)DataGrid Supports UpdataCommand Event that occurs when the UpdateButton is
clicked for an item in the grid.
4)DataGrid is used in Windows GUI Application.
5)It doesnot have EditTemplates for this control
6)It doesnot have AutoFormat
If I write System.exit (0); at the end of
the try block, will the finally block still execute?
Ans:
No in this case the finally block will not execute
because when you say system.exit(0),the control immediately goes out of the
program, and thus finally never executes.
What are the different levels of State
management in ASP.NET?
Ans:
State management is the process by which you
maintain state and page information over multiple requests for the same or
different pages.
There are 2 types State Management:
1. Client – Side State Management
This stores information on the client's computer by embedding the information
into a Web page, a uniform resource locator (url), or a cookie. The techniques
available to store the state information at the client end are listed down
below:
a. View State – Asp.Net uses View State to track the values in the Controls.
You can add custom values to the view state. It is used by the Asp.net page
framework to automatically save the values of the page and of each control just
prior to rendering to the page. When the page is posted, one of the first tasks
performed by page processing is to restore view state.
b. Control State – If you create a custom control that requires view state to
work properly, you should use control state to ensure other developers don’t
break your control by disabling view state.
c. Hidden fields – Like view state, hidden fields store data in an HTML form without
displaying it in the user's browser. The data is available only when the form
is processed.
d. Cookies – Cookies store a value in the user's browser that the browser sends
with every page request to the same server. Cookies are the best way to store
state data that must be available for multiple Web pages on a web site.
e. Query Strings - Query strings store values in the URL that are visible to
the user. Use query strings when you want a user to be able to e-mail or
instant message state data with a URL.
2. Server – Side State Management
a. Application State - Application State information is available to all pages,
regardless of which user requests a page.
b. Session State – Session State information is available to all pages opened
by a user during a single visit.
Both application state and session state information is lost when the
application restarts. To persist user data between application restarts, you
can store it using profile properties.
Abstract Class:
Abstract class is a class which can’t be
instantiate. Class should have “Abstract” key word with the name. In any
one of the method of class having abstract method with in it, then it should be
define as abstract class. The class which derived the abstract class should have
definition of the abstract method. These classes which derived the abstract
class and implement the abstract methods call concrete class.
Abstract class may have the definition of function or may not. Below is
the simple example of an abstract class
public abstract alass AbstractStudent
{
String Roll
{
get;
set;
}
String FirstName
{
get;
set;
}
String LastName
{
get;
set;
}
Public String GetStudentDetails()
{
// Implementation of Method
}
public String SaveStudentDetails ()
{
// Implementation of Method
}
public abstract String
CalculateWage();
}
So, the class having one abstract method so
we need to mention the class as "abstract" .
Difference between Abstract Class and Interface?
Abstract class is a class which can’t be instantiated and which can have
methods with definition as well as declaration also. This can be
inherited.
As for Example:
public abstract class AbstractStudent
{
String Roll
{
get;
set;
}
String FirstName
{
get;
set;
}
String LastName
{
get;
set;
}
Public String GetStudentDetails()
{
// Implementation of Method
}
public String SaveStudentDetails ()
{
// Implementation of Method
}
public abstract String
CalculateWage();
}
Interface can only contain the methods declaration and can be implemented in
the class.
As for Example:
Public interface IStudnet
{
String Roll
{
get;
set;
}
String FirstName
{
get;
set;
}
String LastName
{
get;
set;
}
String GetStudentDetails();
String SaveStudentDetails ();
}
Below are
the few main difference between Abstract Class and Interface
a. In abstract class method can have definition as well as
declaration also. But Interface should have only definition.
b. All the Methods are Public as default and don’t have
any access Modifier Controls in interface, whereas for abstract class we can
have access modifier for methods.
c. Abstract class can have constructor or destructor, whereas
interface not.
d. Abstract class can’t be part of multiple inheritance and
we can implement multiple interface.
What do you mean by String objects are
immutable?
String objects are immutable as its state
cannot be modified once created. Every time when we perform any operation like
add, copy, replace, and case conversion or when we pass a string object as a
parameter to a method a new object will be created.
Example:
String str = "ABC";
str.Replace("A","X");
Here Replace() method will not change data that
"str" contains, instead a new string object is created to hold
data "XBC" and the reference to this object is returned by
Replace() method.
So in order to point str to this
object we need to write below line.
str =
str.Replace("A","X");
Now the new object is assigned to the
variable str. earlier object that was assigned to str will take care by garbage
collector as this one is no longer in used.
What is dll hell problem in .NET and how it
will solve?
Ans:
Dll hell, is kind of conflict that occurred previously,
due to the lack of version supportability of dll for (within) an application
.NET Framework provides operating system with
a global assembly cache. This cache is a repository for all the .net components
that are shared globally on a particular machine. When a .net component
installed onto the machine, the global assembly cache looks at its version, its
public key and its language information and creates a strong name for the
component. The component is then registered in the repository and indexed by
its strong name, so there is no confusion between the different versions of
same component, or DLL
What is a Partial class?
Ans:
Instead of defining an entire class, you can split the
definition into multiple classes by using partial class keyword. When the
application compiled, c# compiler will group all the partial classes together
and treat them as a single class. There are a couple of good reasons to use
partial classes. Programmers can work on different parts of classes without
needing to share same physical file
Ex:
Public partial class employee
{
Public void somefunction()
{
}
}
Public partial class employee
{
Public void function ()
{
}
}
What is difference between
constants, read-only and, static?
Constants: The value can’t be changed
Read-only:
The value will be initialized only once from the constructor of the class.
Static:
Value can be initialized once.
What is
the cross page post backing?
Asp.Net 2.0 fixed
this with built-in features that allowed us to easily send information from one
page to another.
Button control has property PostBackUrl that
can be set to URL of any page in our ASP.Net WebSite where we want to transfer
all form values to.
Along with that Asp.Net 2.0 Page class
has a property PreviousPage that
allows us to get reference to the Page object that initiated the postback (in
other words to get the actual reference to the Page object of the aspx page on
which user clicked the Submit button on a HTML form).
So for example lets create two sample pages in our Web Application:
l SourcePage.aspx
l DestinationPage.aspx
In
SoucePage in Html form we will put two TextBox controls (one for First Name and
one for Last Name) and one Button component and set its PostBackUrl
property to "~/DestinationPage.aspx".
SourcePage.aspx:
<form id="form1" runat="server">
<div>
First
Name: <asp:TextBox
ID="FirstName" runat="server"></asp:TextBox><br />
Last
Name: <asp:TextBox
ID="LastName" runat="server"></asp:TextBox><br /><br />
<asp:Button ID="Button1" runat="server" Text="Submit
To Destination Page" PostBackUrl="~/CrossPagePostbacks/DestinationPage.aspx" />
</div>
</form>
When our user clicks the Submit button, all the values from the HTML Form on
SourcePage.aspx will be transfered to the DestinationPage.aspx and we will also
be able to get reference to the SourcePage.aspx in our DestinationPage with the
PreviousPage property like this:
So in our DestinationPage.aspx.cs code-behind we can easily access two TextBox
controls on SourcePage.aspx and show them in two label controls like this:
protected void Page_Load(object sender, EventArgs e)
{
// first check if we had a cross page postback
if (
(PreviousPage != null) && (PreviousPage.IsCrossPagePostBack)
)
{
Page previousPage = PreviousPage;
TextBox firstName = (TextBox)previousPage.FindControl("FirstName");
TextBox lastName = (TextBox)previousPage.FindControl("LastName");
// we
can now use the values from TextBoxes and display them in two Label controls..
labelFirstName.Text
= firstName.Text;
labelLastName.Text
= lastName.Text;
}
}
You probably noticed that we first checked if PreviousPage property of current page (DestinationPage.aspx) is NOT NULL, this is done to avoid
running our code in case that user opens our DestinationPage.aspx directly,
without running a cross page postback.
Also here we checked the another PreviousPage property called IsCrossPagePostBack to see if we really
had a CrossPagePostback.
(If Server.Transfer is used to redirect to this page, IsCrossPagePostBack property will be set to FALSE.
TIP: We can be completely sure that we have
a real CrossPagePostback ONLY IF:
1. Page.PreviousPage is
NOT NULL,
2. PreviousPage.IsCrossPagePostback is
true
This
important to check to avoid errors in code.
Now this is very useful and i'm sure you are eager to use this in your next
project. But wait, we are not over yet!
Finding the controls on PreviousPage with FindControl method and type-casting
them from object to their real type is a little messy.
It feels like there must be a better solution for this!
And here it is: We can use the <%@
PreviousPageType %> directive in the header of our DestinationPage.aspx
like this
<%@ PreviousPageType VirtualPath="~/SourcePage.aspx" %>
to
declare our previous page type, and then we can access Public properties of the
PreviousPage without typecasting.
Now all we need to do is to create some public properties on our
SourcePage.aspx.cs to expose data/Controls we want to the destionation page:
public partial class SourcePage :
System.Web.UI.Page
{
public string FormFirstName
{
get { return FirstName.Text; }
}
public string FormLastName
{
get { return LastName.Text; }
}
}
And then we can change the Page_Load code in our DestinationPage.aspx to much
cleaner code like this:
protected void Page_Load(object sender, EventArgs e)
{
// first check if we had a cross page postback
if (
(PreviousPage != null) && (PreviousPage.IsCrossPagePostBack)
)
{
SourcePage prevPage = PreviousPage;
// we
can now use the values from textboxes and display them in two Label controls..
labelFirstName.Text
= prevPage.FormFirstName;
labelLastName.Text
= prevPage.FormLastName;
}
}
SourcePage type used in the code is
offcourse name of the partial class defined is SourcePage.aspx.cs that inherits
System.Web.UI.Page
that is automatically created for us when we created new WebForm in
VisualStudio.
This code is much cleaner and easier to follow, there is no ugly typecasting,
just simple property values to use to retrieve the data from previous page.
When should you use Abstract Class vs Interface while
programming?
Ans: When
we want that sub class must implement all the methods of base class. In such a
situation we will implement the interface.
In the other hand when we want only some method of base class in our sub class
then use base class as abstract class.
What is the difference
between application exception and system exception?
Ans:
The difference between application
exception and system exception is that system exceptions are thrown by CLR and
application exceptions are thrown by applications.
What is the difference between authorization and authentication?
Ans: Authorization
is a process of allowing or denying resources to particular user or
record
Declaration of authorization is
<authorization>
<allow
users=”Suresh, Sanjay”/>
<deny
users=”Ramana, Rakesh”>
</authorization>
Sometimes
authorization allows the unauthorized persons at that time we will use
<deny
users=”?”/>
Authentication means
Authentication
is a process where we identify the credentials of user i.e. username, password
and create an identity to mention user as an authenticated.
What is the use of n-tier architecture and 3-tier architecture?
Check this article for 3-tier architecture 3 tier architecture example in asp.net
How to get the version of the assembly?
Ans: lbltxt.text=Assembly.
GetExecutingAssembly().GetName().Version.ToString();
What is the location of Global Assembly Cache on the system?
Ans: c:\Windows\assembly
What is the serialization?
Ans: Serialization
is a process of converting object into a stream of bites.
What is synchronization?
Ans: The
mechanism needed to block one thread access to the data. If the data is being
accessed by another thread.
Synchronization
can be accessed by using system.monitor
class
A
monitor class methods are enter, exit, pulse for this lock statement is also
used
Suppose
if we need to synchronize some data at that time we need to place that data in
this block
Lock
{
}
Whatever
the data has been placed into the lock block that data has been blocked
What are the thread priority levels?
Ans: Thread
priority levels are five types
0
- Zero level
1
- Below Normal
2
- Normal
3
- Above Normal
4
- Highest
By
Default priority level is 2
What is the difference between .tostring(), Convert.tostring()?
Ans: The
basic difference between them is “Convert” function handles NULLS while
“.ToString()” does not it will throw a NULL reference exception error. So as a
good coding
practice using “convert” is always safe.
What is Collation?
Ans: Collation
refers to a set of rules that determine how the data is sorted and compared.
What is the difference between Primary key and unique key?
Ans: Primary
key does not allow the null values but unique key allows one null value.
Primary
key will create clustered index on column but unique key will create
non-clustered index by default.
How many web.config files are there in 1 project?
Ans: There
might be multiple web.config files for a single project depending on the
hierarchy of folders inside the root folder of the project, so for each folder
we can use one web.config file
What is the difference
between throw and throw ex?
What is the difference
between view state and hidden field?
Ans: viewstate
is secured hidden field is insecure
Viewstate
will store large amount of data but hidden filed will store small amount of
data.
What is the difference
between binary serialization and xml serialization?
What is the Difference
between read only and constant variables?
Ans: Read
only can assign the values at runtime only.
Constant
will assign the values at compile time only.
We
cannot modify the both variable values.
What is static keyword
in .Net?
Ans: Static
is same as constant variable but we can change the value of static variable and
we can access the variables without creating any instances
What is the use of
business logic layer in 3-tier architecture in .net?
Ans:
Though
a web site could talk to the data access layer directly, it usually goes
through another layer called the business layer. The business layer is vital in
that it validates the input conditions before calling a method from the data
layer. This ensures the data input is correct before proceeding, and can often
ensure that the outputs are correct as well. This validation of input is called
business rules, meaning the rules that the business layer uses to make
“judgments” about the data.
However, business rules don’t only apply to
data validation; these rules apply to any calculations or any other action that
takes place in the business layer. Normally, it’s best to put as much logic as
possible in the business layer, which makes this logic reusable across
applications.
One
of the best reasons for reusing logic is that applications that start off small
usually grow in functionality. For instance, a company begins to develop a web
site, and as they realize their business needs, they later decide to add a
smart client application and windows service to supplement the web site. The
business layer helps move logic to a central layer for “maximum reusability.”
