Validating User Credentials

Validating User Credentials
---------------------------------

Let us see how to validate the user credentials(login and password)

In aspx.cs under Button_Click() method write the following code

string email= txtemail.Text;
string password = txtpassword.Text;

SqlConnection con = new SqlConnection(connectionstring);
string str = “select * from UserLoginInfo where email=’ ” + email + “ ‘ and password = ‘ “ + password + “ ‘ “;
SqlCommand cmd = new SqlCommand(str, con);

try
{
con.Open();
SqlDataReader dr = cmd.ExecuteReader();
bool userexists = false;

while(dr.Read())
{
userexists = true;
}
if(userexists)
{
Server.Transfer(“Nextpage.aspx”);
}
else
{
lblresult.Text = “ Please enter the valid email and password”;
}
catch(exception e)
{
throw e;
}
finally
{
con.Close();
}
}

Here we are taking the user entered values(textbox values) into strings and checking them with the values in table UserLoginInfo. If both the values matches then the variable userexists becomes true and you will be derected to another(in this case Nextpage.aspx) page otherwise user will get the message “please enter the valid email and password.

In .aspx page create 2 textboxes for email and password and 1 submit button. In button_click method write the above code.

3-Tier Architecture

3-Tier Architecture
-----------------------
Today Iam going to discuss about the 3-Tier Architecture .

PresentationLayer: This is the layer through which user enters the values or values are shown to the user.
BusinessAccessLayer: This layer is used to perform calculations, validations and write business logic.
DataAccessLayer: This layer is used to connect to the database and perform the required actions which may be inserting, deleting, updating values to database or from database.

First create a table with firstname, lastname, age as its columns. Then write a storedprocedure to insert values in to that table.

Then in the project create a class library with the name DataAccessLayer.In this class library create a class with the name UserInformationDAO and write the following code

public class UserInformationDAO
   {
public void InsertUserInfo(string firstname, string lastname, int age)
     {
       SqlConnection con = new SqlConnection(connectionstring);
       SqlCommand cmd = new SqlCommand(“InsertUserData”, con);
       cmd.CommandType = CommandType.StoredProcedure;

cmd.Parameters.Add(“@firstname” , SqlDbType.Varchar, 30).value = firstname;
cmd.Parameters.Add(“@lastname” , SqlDbType.Varchar, 30).value = lastname;
cmd.Parameters.Add(“@age” , SqlDbType.Int).value = age;

try
       {
         con.Open();
         cmd.ExecuteNonQuery();
       }
catch(Exception e)
       {
         throw e;
       }
finally
       {
         con.Close();
       }
      }
   }

In the above code connectionstring means connection parameters. Which contains servername,databasename, userid, password.
InsertUserData is the name of the storedprocedure to insert values in to the
table. @firstname,@lastname,@age are the storedprocedure variables.Using cmd.Parameters.Add we are adding values to cmd.


Now once again create a class library named BusinessAccessLayer and create a class in that named UserInformationBAO.

public class UserInformationBAO
{
private string firstname;
private string lastname;
private int age;

public string FirstName
       {
          get { return firstname;}
          set { firstname = value;}
       }
public string LastName
       {
           get { return lastname;}
          set { lastname = value;}
       }
public int Age
       {
          get { return age;}
          set { age = value;}
       }

public void InsertUserInfo()
       {
          UserInformationDAO uinfo = new UserInformationDAO()
          uinfo. InsertUserInfo(FirstName, LastName, Age);
       }
}

In the above code we have written 3 properties. In InsertUserInfo method we are creating an object of UserInformationDAO class, using that we are invoking the method InsertUserInfo of UserInformationDAO class.


In .aspx.cs page you need to write the following code to read values from textboxes.

protected void btnsubmit_Click(object sender, EventArgs e)
       {
          UserInformationBAO uinfobao = new UserInformationBAO();

          uinfobao.FirstName = txtfirstname.Text;
          uinfobao.LastName = txtlastname.Text;
          uinfobao.Age = txtage.Text;
          uinfibao.InsertUserInfo();
       }

Here first we are creating an object of UserInformationBAO class and using that object we are reading the values in to properties.

In .aspx page you will have 3 textboxes for firstname, lastname and age. Below these you should create a button so that when this button is clicked values from text boxes will be saved in to database.

<div>
<table>
<tr>
<td>
<asp:Label ID=”lblfirstname” runat= “server”>FirstName </asp:Label>
<asp:Textbox ID=”txtfirstname” runat = “server” ></asp:Textbox>
</td>
</tr>

<tr>
<td>
<asp:Label ID=”lbllastname” runat= “server” >LastName</asp:Label>
<asp:Textbox ID=”txtlastname” runat = “server” ></asp:Textbox>
</td>
</tr>

<tr>
<td>
<asp:Label ID=”lblage" runat= “server” >Age</asp:Label>
<asp:Textbox ID=”txtage” runat = “server” ></asp:Textbox>
</td>
</tr>

<tr>
<td>
<asp:Button ID=”btnsubmit” runat= “server” Text = “Submit” OnClick= “btnsubmit_Click”></asp:Button>
</td>
</tr>
</table>
</div>

Binding Data to Dropdownlist from Database

Binding Data to Dropdownlist from DataBase
---------------------------------------------------------------
Today Iam going to write on Binding Data to Dropdownlist from Database

Consider that we want to populate the Dropdownlist with a list of countries. For this first we need to create a new .aspx page with the following code

<asp:dropdownlist id =" “dpdcountry”" runat="”server”">
</dropdownlist>

Now create a new classlibrary with the class name DataBinding.cs and write the following code

public class Databinding
{
public static DataTable Execute(string sqlstring)
{
SqlConnection con = new SqlConnection(connectionstring);
DataTable dt = new DataTable(“tb1”);
try
{
con.Open();
SqlCommand cmd = new SqlCommand(sqlstring, con);
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(dt) ;
}
catch(Exception e)
{
throw e;
}
finally
{
con.Close();
}


return dt;
}
}


In the above code Databinding is the class name, Execute is the method which returns a datatable. In the connectionstring you need to specify the 4 parameters of the SqlConnection string.

Now in the .aspx.cs file under Page_Load method you need to write the following the code

If(!IsPostBack)
{
string str = “select country_id , name from Country”;
Datatable dt = Databinding.Execute(str);
dpdcountry.DataValueField = dt.columns[0].ToString();
dpacountry.DataTextField = dt.cloumns[1].ToString();
dpdcountry.DataSource = dt;
dpdcountry.DataBind();
}



On a whole, first we declared a dropdownlist with the name dpdcountry in the .aspx page. Then in .aspx.cs page, in the Page_Load method we are sending the sql string to the class Databinding which connects to the database and returns the data table containg the country names. Then this data table is assigned to the dropdownlist as its datasource. So, when you run this code you get a page with the dropdownlist populated with country names.
Note:
1. You should add the Class Library name in the Referrences of the Project
2. You should use the Class Library name in the directories part of the .aspx.cs page

C# InterviewQuestions-Part 10

Interview Questions
----------------------
91. How many types of errors are there?
a ) 2 types
1. Run time errors
2. Compile time errors

92. Give some examples of compile time and runtime errors?
a ) Compile time:
missing semocolons
use of undeclared variables
bad references to objects
runtime:
dividing an integer by zero
using negative size for an array
passing a parameter that is not in a valid range

93. What is an exception?
a ) An exception is a condition that occurs by a run time error in the program

94. What is the base class used for all the exceptions in c#?
a ) It is Exception

95. Why do we use throw keyword?
a ) Throw keyword is used to throw our own exceptions.

96. How many exceptions we can write in throws clause?
a ) We can use multiple exceptions.

97. Can a finally block exists with try block but without a catch block?
a ) Yes

98. Can we have nested try blocks in c#?
a ) yes

99. What is the difference between Write() and WriteLine() methods?
a ) Write() method outputs one or more values to the screen without a newline character
WriteLine() method outputs one or more values to the screen with a newline character

100. What is the difference between Read() and Readline() methods?
a ) Read() method returns a single character as int
ReadLine() method returns a string containing a line of text

C# InterviewQuestions- Part 9

81. why we use the ref keyword?
a ) If you want to pass a parameter by reference you should use the keyword ref

82. If an out parameter is not assigned a value with in the body of the function does that method complile?
a ) No. it won't compile

83. How can you make write a read only property?
a ) A property can made a read only by omitting the set accessor from the property defination.

84. When a static constructor is executed?
a ) It is executed when the class is loaded.

85. How many preprocessor directives exists in c#?
a ) They are #define, #undef, #if, #elif, #else, #endif, #error, #warning, #region, #endregion, #pragma etc

86. When an instance constructor is executed?
a ) It is executed when an instance is created.

87. Where you can assign values to a read only field?
a ) We can assign inside a constructor

88. Why we use the sixeof operator?
a ) If we want to know the size of any data type you can use sizeof operator.

89. What are the disadvantages of distructors in c#?
a ) 1. They are non deterministic. means there is no way to know when an object's destructor will actually execute.
2. Implementation of destructor delays the final removal of an object from memory. means objects that have destructors are removed in 2 passes. in the 1st pass only the destructor will be called with out removing object and then the 2nd pass removes the object, which is time taking and which may effect the performance.

90. What is the default access modifier of an interface members?
a) public

C# InterviewQuestions- Part 8

Interview Questions
-----------------------------

71. Can we declare an abstract method in non abstract class?
a ) No. it can declared only in abstract classes

72. Can we use static or virtual keywords to an abstract method?
a ) No

73. Can an interface extend a class?
a ) No. it can’t extend classes.

74. Is it necessary that the direct base class of a derived class must be at least as accessible as the derived class itself?
a ) Yes.

75. What is the keyword that is used to invoke the constructor method of the super class?
a ) It is the keyword “base”.

76. What is an enumeration?
a ) An enumeration is a user-defined integer type which provides a way for attaching names to numbers.

77. What is boxing?
a ) Conversion of value type to object type (reference type) is known as boxing

78. What is unboxing?
a ) Conversion of object type to value type is known as unboxing.

79. What are the categories of variables that are automatically initialized to their default values?
a ) They are
1. Static variables
2. Instance variables
3. Array elements

80. What is the scope of a variable?
a ) Scope of a variable is the region of code with in which the variable can be accessed.

C# InterviewQuestions- Part 7

Interview Questions
----------------------------
61. Can private virtual methods be overridden ?
a ) No. we can not access private methods in inherited classes.

62. Can we inherit multiple interfaces?
a ) yes. In c# multiple inheritance is achieved through interfaces.

63.How can a method be overloaded?
a ) a method can be overloaded by creating a method with the same name but with different parameter order, data types and number

64. Will finally block get executed if the exception had not occurred?
a ) Yes. Finally block always gets executed regardless of an error.

65. Can multiple catch blocks be executed ?
a ) No. once the appropriate catch code is fired control transfer to the finally block then continues with the rest of the code.

66. What is the accessibility level of a protected variable?
a ) It is available to the classes in the same name space.

67. Can you override private virtual methods
a ) No.

68. Can we inherit multiple interfaces?
a) Yes. We can’t inherit multiple classes but we can inherit multiple interfaces.

69. Can we use virtual keyword to a destructor?
a ) No

70. What is the access level of a internal variable?
a ) current assembly

C# InterviewQuestions- Part 6

Interview Questions
---------------------------
51. What are the types of strings?
a ) 2 types
1. mutable strings
2. immutable strings

52. Is a string is a reference type or value type?
a ) A string is reference type

53. What do you mean by mutable and immutable ?
a ) Mutable means we can alter the characters contained in them.
Immutable means that we can not alter the characters contained in them

54. What are String and StringBuilder classes?
a ) String class is an immutable class and
StringBuilder class is an mutable class

55. Tell me some methods present in StringBuilder class?
a ) They are
Append(),
Insert(),
Remove(),
Replace(),
appendFormat()

56. What is the namespace of StringBuilder class?
a ) System.Text

57. Tell me some methods present in String class?
a ) They are
Copy(),
Equals(),
ConCat(),
Compare(),
Trim(),
Substring(),

58. Can you store multiple data types in System.Array ?
a ) No.

59. What is the class from which an array is created(derived) automatically in c#
a ) System.Array

60. Some common methods of System.Array class?
a ) Clear(), CpoyTo(), GetValue(), Sort(), Reverse() etc.

C# InterviewQuestions- Part 5

41. How can we achieve multiple inheritance in c#?

a ) Using interfaces.

42. An interface is a value type or reference type?

a ) An interface is a reference type.

43. Does an interface extend classes?

a ) No

44. Can we write constructors and destructors for an interface?

a ) No.

45. What are the default modifiers of members of an interface?

a ) Public and abstract

46. What are the differences between an abstract class and an interface?

a ) Abstract class

1. it can contain implementation to some methods.

2. we can apply access modifiers to one or more methods in an abstract class

3. a class can not inherit more than one abstract class

4. an abstract class can have fields and constants defined

Interface

1. it just contains declarations. No implementation for any method.

2. we can not apply access modifiers to methods inside an interface

3. a class can inherit more than one interface

4. interface does not contain any field definition.

47. Can an interface is implemented by any number of classes?

a ) Yes.

48. What are the types of polymorphism?

a ) 2 types

1. operation polymorphism

2. inclusion polymorphism

49. How we achieve operation polymorphism and inclusion polymorphism?

a ) Operation polymorphism is achieved using overloaded methods and operators

And inclusion polymorphism is achieved using virtual functions.

50. what do you mean by compile time polymorphism?

a ) It is a process of selecting and binding the appropriate method to the object for a particular call at compile time.

C# InterviewQuestions- Part 4

Interview Questions
---------------------------
31. What are the inheritance types?
a ) 1. single level inheritance
2. multi level inheritance
3. multiple inheritance
4. hierarchical inheritance

32. Can we inherit the private members of a class
a ) Yes. But they are not accessible.

33. Why we use the keyword virtual?
a ) When you want to override a method of base class in derived class you should use this virtual keyword to the method in base class

34. Why we use override keyword?
a ) When you want to override a method of base class in derived class you should use this override keyword to the method in derived class

35. What are the abstract classes?
a ) Abstract classes are the classes for which we can not create objects. Means an abstract class can not be instantiated.

36. What are abstract methods?
a ) Abstract methods are the methods which does not contain their body part means they does not provide any implementation.

37. What are the properties of abstract methods?
a ) 1. they do not contain body part.
2. their definition/implementation should be given in non-abstract classes by overriding that method.
3. we can not use static modifier to it.

38. What are the sealed classes?
a ) If you want to prevent a class from being inherited you can use this keyword sealed to that particular class

39. What are sealed methods?
a ) A sealed method is a method which can not be overridden by its derived class.

40. Does a sealed class is an abstract class? Why?
a ) No a sealed class is not an abstract class. Because we can’t inherit a sealed class but we can inherit an abstract class.

C# InterviewQuestions- Part 3

Interview Questions
--------------------------

21. What are the properties of constant members?
a ) 1. They should use the modifier ‘ const’
2. Their value should be given when they are defined (it can’t be changed later)
3. They are implicitly static.

22. Why we use this keyword?
a ) This is used to distinguish local and instant variables that have the same name.

23. Does a copy of a static variable is created every time a class is instantiated?
a ) No.

24. What is a partial class?
a ) A partial class is a class which resides in multiple files. It should use 'partial' keyword. Generally it is used in situations where multiple developers need acess to the same class.

25. What is the name of the class from which all .net classes are derived?
a ) System.Object

26. Does c# support global variables?
a ) No. all declarations must be done inside a class.

27. Differences between property and indexer?
a ) Property
A property can be static member
The get accessor of a property corresponds to a method with no parameters
Indexer
An indexer is always an instant member
The get accessor of an indexer corresponds to the same formal parameter list as the indexer.

28. Differences between overloading and overriding?
a ) Overloading
1. used we want a method with more than one definition with in the same scope
2. in overloading, methods will have same name but different number, types, order of arguments.
Overriding
1. this is used when we have parent, child classes.
2. in overriding , methods will have same name with same arguments and same return type.

29. what is the order of the constructor execution in inheritance?
a ) They are executed from top(parent class) to bottom(child class)

30. what is the order of the destructors execution in inheritance?
a ) They are executed from bottom(child class) to top(parent/base class)

C# InterviewQuestions- Part 2

Interview Questions
---------------------------

11. Can we use access modifier on static constructor?
a ) No

12. How many static constructors we can declare for a single class?
a ) A class can have only one static constructor.

13. What is method overloading?
a ) It is a process of creating methods that have the same name but with different parameter lists and different definitions. This method overloading is used when you want your methods to do same tasks but using different input parameters.

14. What happens when we use ‘private’ modifier to a constructor of a class?
a ) When we declare a constructor of a class as private then we can’t create a objects of that class and we can not use that class as a base class for inheritance

15. Can we overload constructors?
a ) Yes

16. What are instant variables?
a ) Class variables are known as instant variables. Instant variables are different for each object and they are accessed using the objects. When ever a class is instantiated a new copy of the each of the instant variable is created.

17. What are static variables?
a ) These are also known as class variables. Static variables are common for all objects of a class. Only one copy of static variables will be created for all the objects of a class.

18. What are the differences between structure and class
a ) Structure:
It is value type
It is stored on stack
Does not support inheritance
Suitable for small data structure
Class:
It is reference type
It is stored on heap
Supports inheritance
Suitable for complex data structures

19. What is a value type? Give examples
a ) It stores value directly. Value types are stored on stack. Separate memory will be given for each instant of a value type.
Ex: int, float, char, struct

20. What are reference type?
a ) It stores a reference to the value. They are stored on heap.
Ex: class, string, array.

C# InterviewQuestions- Part 1

Interview Questions
------------------------

1. What are the main properties of object oriented programming?
a ) There are mainly 3 properties
1. Encapsulation/Abstraction
2. Inheritance
3. Polymorphism

2. What is encapsulation?
a ) This gives a way to hide the internal details of an object from its users.

3. What is inheritance ?
a ) It provides a way to build/create new classes using existing classes.

4. What is polymorphism?
a ) It provides a way to take more than one form.

5. What is a constructor?
a ) Constructor enables an object to initialize itself when it is first created.

6. What are the properties of a constructor?
a ) They are
1. They should have the same name as that of a class
2. They do not specify a return type.
3. we can use access modifiers to constructor.

7. How many types of access modifiers are there ?
a ) 5 types
1. Private
2. Public
3. Protected
4. Internal
5. Protected Internal

8. What access modifiers we can use for a class?
a ) We can use 2 access modifiers
1. Public
2. Internal

9. What is the default access modifier of a class?
a ) It is Internal

10. What is the default access modifier for class members?
a ) It is Private

DataSet

Filling dataset with data from more than one table
------------------------------------------------------------
To Fill dataset with data from more than one table from database and to
bind that data to datagrid we need following code

1. In .aspx file you need to write

<div>
<asp:datagrid id="grid1" runat="server" autogeneratecolumns="True">
</asp:datagrid>
<asp:datagrid id="grid2" runat="server" autogeneratecolumns="True">
</asp:datagrid>
</div>

Here we are specifying 2 datagrids to display data from 2 Tables.

2. In .aspx.cs file

1. First we need to open a connection

SqlConnection newconn = new SqlConnection(“Server=xxx;
InitialCatalog=xxx; UserId=xx;Password=xxx”);
Newconn.open();

In the above statement server= xxx means we are specifying server
name.InitialCatalog means database name from which we want to
retrive data. Userid, password are userid and passwords of user
for sql server.

2. Next we need to specify the sql statements(required operation)

DataAdapter da = new SqlDataAdapter("select * from firsttablensme;
Select * from secondtablename”, newconn)

note: here instead of command object we are directly using
DataAdapter.If you want you can use command object also.

In the above statement we are selecting data from two tables.
Newconn is the connection object.

3. Now, we need to fill the dataset

ds = new DataSet();
da.Fill(ds, “firsttablename”);
da.Fill(ds, “secondtablename”);

Here we are using Fill() method of dataadapter to fill the Dataset.

4. Now to bind this data to datagrid we need following code

grid1.DataSource = ds;
grid1.DataSource = ds.Tables[0];
grid1.DataBind();

grid2.DataSource = ds.Tables[1];
grid2.DataBind();

Here DataSource property represents the datasource of the datagrid and
DataBind() method used to bind data to the datagrid.

Note: you can also use caption property of datagrid to specify the table caption
Ex: grid1.caption = “xxx”
here Xxx represents cation for the table displayed by datagrid.

That’s it.

Filling data from Database in to Dataset and then to Datagrid

LOADING DATA FROM DATABASE IN TO DATASET AND BINDING IT TO DATAGRID
---------------------------------------------------------------------------------
Dataset can not directly retrieve data from database. For this purpose we should use DataAdapter. DataAdapter acts as a bridge between database and dataset. This is used to retrieve data from Database into Dataset as well as to Update Database through Dataset.It supports insert, delete, update, select operations. It supports disconnected model.

Now we will see the steps required to fill data from database into dataset and then populate that data into datagrid.
For that

In .aspx page, in <div> section we should write
<div>
<asp:datagrid id="exdatagrid" autogeneratecolumns="true" runat="server">
</asp:datagrid>
</div>

Here ID represents the id of the datagrid, runat represents that the datagrid is a server control, AutoGenerateColumns automatically creates the columns for the datagrid.

In the .aspx.cs file

1. First we should open a connection
SqlConnection newconn = new SqlConnection(“Server=xxx;InitialCatalog=xxx;
UserId=xx;Password=xxx”);
Newconn.open();

In the above statement server = xxx means we are specifying server name. InitialCatalog means database name from which we want to retrive data. Userid, password are userid and passwords of user for sql server.

2. Next we need to specify the sql statement(required operation)

SqlCommand cmd = new SqlCommand(“select * from xxx”, newconn);

In this statement first argument specifies the sql select statement(required operation) and second statement specifies the connection object. Here xxx represents Table name in database.

3 Now, we need to declare the DataAdapter

SqlDataAdapter da = new SqlDataAdapter(cmd);

In this statement dataadapter contains the command object as its argument to perform the required operation.

4. Now, we need to fill the dataset

ds = new DataSet();
da.Fill(ds);

In these statements first we declare dataset and then using the Fill() method of dataadapter we fill the dataset with the data from Database.

so now dataset is filled with the data from database.

5. Now we fill datagrid with the information/data in the dataset

exdatagrid.DataSource = ds;
exdatagrid.DataBind();

Here exdatagrid is the id of the datagrid we have declared in .aspx page.
DataSource property represents the datasource(means dataset) for the datagrid. DataBind method is used to bind data to the datagrid.

That’s it. We will see the data populated in to the datagrid.

Interview Questions - Part 10

Interview Questions
--------------------------

96. What is a TreeView Server control ?
a ) This is a site navigation control. It displays the data in hierarchical order. Generally is is used to display Menu items for an application. It contains a number of prebuilt styles.

97. What are the differences between viewstate and hidden fields?
a ) Viewstate :
1. This is used for pages that will postback to itself
2. This is a built in structure for maintaining state of a page
3. Security is more as data is hashed, compressed and encoded.
Hiddenfield :
1. This is used for pages that will postback to itself or to another page
2. This is not an inbuilt structure
3. Security is less when compared to viewstate

98. Examples of Navigation controls?
a ) They are
1. TreeView Control
2. Menu
3. SiteMapPath

99. What is the namespace used for web page
a ) System.Web.UI.Page

100. What is the use of IsPostBack method?
a ) This method is to determine whether request is new request or postback request.

101. What are the advantages of DataGrid Control?
a )
1. Inbuilt support for paging and sorting
2. Inbuilt support for user selection and editing
3. Contains its default display

Interview Questions - Part 9

Interview Questions
--------------------------
86. What is caching?
a ) This allows a way to keep most frequently used data in memory to increase the performance of the application.

87. What are the types of page output cache?
a ) This is used to store the contents of a processed page in memory.
It is devided in to 2 types
1. full page caching
it stores the entire contents of a page
2. partial page caching
it stores the parts of a page.

88. What do you mean by post-cache substitution?
a ) This is one type of partial page caching. It allows you to cache the entire page but parts of a page are not cached means they will be created dynamically.

89. When the items will be removed from the cache?
a ) Items from cache are removed
1. when memory runs low
2. when an item expires
3. when items dependency changes

90. What is Sliding expiration?
a ) Suppose an item is placed in cache and its sliding expiration is 10 minutes. Then this sliding expiration policy specifies that the item stored in cache will be removed after 10 min from the time it is last used/accessed.

91. What is Absolute expiration?
a ) Suppose an item is placed in cache and its absolute expiration is 5 pm. Then this absolute expiration policy specifies that the item will be removed from the cache after 5 pm.

92. What is the directive used to implement caching in a page?
a ) It is @OutputCache

93. What is the attribute used to set the expiration of an item in the cache?
a ) It is “Duration” attribute

94. What are the attributes of outputcache used to store multiple versions of a page?
a )
1. VaryByParam
Using querystring it enables you to cache multiple versions of a page
2. varyByControl
Using a control value it enables you to cache multiple versions of a page
3. VaryByHeader
Using requests http header it enables you to cache multiple versions of a page
4. VaryByCustom
Using custom string or browser type it enables you to cache multiple versions of a page

95. what is sql dependency in caching?
a ) Means an item in the cache depends on the changes in a table in sql Database.

Interview Questions - Part 8

Interview Questions
---------------------------

76. What is the life time of the data stored in viewstate?
a ) Data stored in viewstate exists for the life of the current page.

77. Can a masterpage contain multiple content areas?
a ) Yes

78. What does the merge method of dataset do?
a ) It merges the dataset with another dataset.

79. What is the maximum length of the char datatype?
a ) Char – max of 8000 characters

80. What is the method used to kill a session explicitly?
a ) Session.abandon method.

81. What is the extension of the resource files?
a ) .resx

82. What is the attribute used to apply theme to a specific page?
a ) That is ‘Theme’ attribute.

83. How many types of configuration files are there?
a ) 2 types
Machine.config: This is a server or machine wide configuration file
Web.config : This is a application configuration file.

84. What are the advantages of web.config file?
a )
1. This contains application specific configuration settings whichis same for all the pages in that application.
2. This is xml file which is easily readble and understandable.
3. This applies changes to the asp.net application with out need for the administrator to stop and start the webserver.
4. It provides more security as data is encrypted.

85. Is it possible for an application to have more than one web.config file?
a ) Yes. An application can support more than one web.config file.

Interview Questions - Part 7

Interview Question
--------------------------

66. What are the types of Serialization?
a ) 4 types
1. XML Serialization
2. Binary Serialization
3. SOAP Serialization
4. Custom Serialization

67. What is xml serialization?
a. ) Xml serialization can convert only the public properties and fields of an object in to an xml stream that confirms to a specific xml schema defination language document. Xml serialization is also known as shallow serialization. Xml serialization is used when you nedd the data in the object to stored in xml format. Xml stream can be processed by any application as needed regardless of platform.

68. What are the 2 methods of xmlserializer class?
a ) 1. serialize
2. deserialize

69. What is binary serialization?
a ) This is used to convert both public and private properties and fields of an object. This serialization is useful when data needs to travel electronically over wire. Disadvantage of this serialization is it is not easily portable to another platform.

70. What is SOAP Serialization?
a ) Similar to binary serialization this also convert the public and private properties and fields of an object in to a stream of bytes. This serialization is useful when you need interoperability.

71. what is satellite assembly?
a) An assembly which contains language specific resouces means culture information is known as satellite assembly.

72. what are the parts of version number of an assembly?
a) They are major, minor, revision, build.

73. what are the commands used to insert and remove assemblies in/from global assembly cache?
a) gacutil -I assemblyname /to insert
gacutil -u assemblyname /to uninstall

74. In which suituations we use gacutil tool?
a) We use it in development scenarios.

75. what is side-by-side execution?
a) This provides a way to keep multiple versions of an application on the same machine at the same time.

Interview Questions - Part 6

Interview Questions
-----------------------------

56. How can we customise columns in datagrid?
a ) Using the Template column.

57. What is the character/size limit in query string?
a ) Some browsers impose a 2083 character limit on the length of the URL.

58. How do you separate business logic while creating on asp.net application?
a ) By using code behind model

59. How many classes can a single .net dll contain?
a ) It can contain unlimitesd classes.

60. What is the maximum length of varchar and nchar datatypes?
a ) Varchar - max of 8000 characters
Nchar - max of 4000 characters

61. What is Portable Executable?
a ) It is a file format defining the structure that all executable files and dynamic link libraries must use to allow them to be loaded and executed by windows.

62. What is the use of Application Domain?
a ) This provides a way to isolate an application from other applications.

63. In which folder we store Local Resouce files?
a ) They are specific to a single page. They are stored in App_LocalResorces

64. What is serialization? What are its advantages?
a ) It provides a way to save the state of an object by converting it into a stream of bytes.
Advantages:
1. It provides a way to transportation of an object through a network
2. It provides a way to re create the same object by saving the its state.

65. What are the disadvantages of serialization?
a )
1. It requires more resources (to convert an object into a stream of bytes)
2. Serialization is a slow process.
3. It involves latency issues for transmitting the data over network.