Asp.net Interview

2. What is the difference between a Hash Table and a Dictionary?

The main differences are listed below.

Dictionary:

    Returns an error if the key does not exist
    No boxing and unboxing
    Faster than a Hash table

Hashtable:

    Returns NULL even if the key does not exist
    Requires boxing and unboxing
    Slower than a Dictionary

3. How to use View state?

    string str = "Sibeesh Passion"; 
    if(ViewState["SampleText"]==null) 
    { 
       ViewState["SampleText"] = str; 
    }  

4. What are the state management techniques used in .NET?

Client-side:

    Hidden Field
    View State
    Cookies
    Control State
    Query Strings

Server-side:

    Session

        In Proc mode
        State Server mode
        SQL Server mode
        Custom mode

    Application.

Read here.

5. How can we create a new table in SQL with only the structure?

Here is the query to do that.

    Select * Into<B>From<A>Where1 = 2

Points to be noted:

    A is the source table.
    B is the destination table.
    The condition 1=2 is to prevent the data from being copyied.

6. How to add a button dynamically to a grid view?

        Button myButton = newButton(); 
        myButton.Text = "Hai"; 
        myGrid.Controls.Add(myButton);  

7. How to find a control inside a GridView?

    Button btnTest = (Button) myGrid.Rows[0].Cells[1].Controls[1].FindControl("myButton ");  

Here we are finding the control myButton from the 0th row first cell.



9. What is partial class?

There are the following situations of when splitting a class definition is desirable:

    To work with large projects.
    To split the class definitions as we needed with the keyword partial.

10. How to use a partial class?

        public partial class DailyExpenses 
        { 
            To make it more real, let us consider this class is used by the Husband .  
            He will add his expenses (in programming life , his codes ) 
            public void AddExpensesByHus() 
            { 
            } 
        } 
        public partial class DailyExpenses 
        { 
           To make it more real, let us consider this class is used by the Wife.  
           She will add his expenses (in programming life , her codes ) 
           public void AddExpensesByWife() 
            { 
            } 
        }  

11. How to remove a constraint from a table in SQL Server?

        ALTER TABLE MyTab DROP CONSTRAINT myConstraint  

12. How to create Table Variables In T-SQL?

Normally the syntax to create a table variable is the same as to create a table statement.

        DECLARE@tabVar TABLE 
        ( 
           Your fields here 
        )  

13. How can you delete a duplicate record from a table in SQL?

There are so many ways to do this. Here I am sharing what I use when I get that kind of situation.

I will create a temp table.

Copy the distinct data from the existing table to the temp table.

Empty the data in the existing table.

Insert the data from the temp table to the source table.

Here is the query to do that:

    select distinct * into #tempTab From Address_Tab
    delete from Address_Tab
    insert into Address_Tab
    select * from # tempTab
    drop table # tempTab 

SELECT name, COUNT(email) FROM users GROUP BY email HAVING ( COUNT(email) > 1 )

14. When to use an override and new in C#?

    We can use override when there is virtual/abstract/override type of method in base class.
    We can use New when there is no virtual/abstract/override type of method in base class.

That is all for today. I will see you soon with another set of questions and answers.

Please provide your comments and suggestions thanks in advance.