Take backup all database from sql server using cursors

DECLARE @name VARCHAR(50) -- database name 

DECLARE @path VARCHAR(256) -- path for backup files 

DECLARE @fileName VARCHAR(256) -- filename for backup 

DECLARE @fileDate VARCHAR(20) -- used for file name

SET @path = 'C:\Backup\' 

SELECT @fileDate = CONVERT(VARCHAR(20),GETDATE(),112)

DECLARE db_cursor CURSOR FOR 

SELECT name

FROM MASTER.dbo.sysdatabases

WHERE name NOT IN ('master','model','msdb','tempdb') 

OPEN db_cursor  

FETCH NEXT FROM db_cursor INTO @name  

WHILE @@FETCH_STATUS = 0  

BEGIN  

       SET @fileName = @path + @name + '_' + @fileDate + '.BAK' 

       BACKUP DATABASE @name TO DISK = @fileName 

       FETCH NEXT FROM db_cursor INTO @name  

END  

CLOSE db_cursor  

DEALLOCATE db_cursor

How to remove duplicate records from datatable in c#

 private DataTable RemoveDuplicatesRecords(DataTable dt)

 {

    var UniqueRows = dt.AsEnumerable().Distinct(DataRowComparer.Default);

    DataTable dt2 = UniqueRows.CopyToDataTable();

    return dt2;

  }

Difference between a Class and an object ?

Class: 

1)It is a datatype that contains the programming logic. 
2)Class is visible in the source code and resides in hard disk. 
3)Class is like a template or blueprint of the object. It implements reusability, 
encapsulation, inheritance 
example:Button is a class with properties like Text,BackColor, 
events like click, methods like Focus 

Object: 
1)it is a chunk of memory that implements the class logic. 
2)Object is in the RAM and not visible in source code. 
3)It is the real world implementation of the class. 
Each object has its own copy of data. 
example: Button1, Button2 are the objects of Button class.

Difference between Value Type and Reference Type ?

Value type	Reference type
Value type they are stored on stack	Reference type they are stored on heap
When passed as value type new copy is created and passed so changes to variable does not get reflected back	When passed as Reference type then reference of that variable is passed so changes to variable does get reflected back
Value type store real data	Reference type store reference to the data.
Value types are faster in access	Reference types are slower in access.
Value types derive fromSystem.ValueType	Reference types derive fromSystem.Object
Value type consists of primitive data types, structures, enumerations.	Reference type consists of class, array, interface, delegates
Value types can not contain the valuenull.	Reference types can contain the valuenull.

Converting Array to List

using System.Linq;

List<datatype> list = array.ToList();

Comparing two datatables and returning a datatable by matching rows in c#.net using linq

  public DataTable get_Comparing(DataTable dt1, DataTable dt2)

   {

      DataTable dtMerged = (from a in dt1.AsEnumerable()

                                  join b in dt2.AsEnumerable()

                            on a["Student_Id"].ToString() equals b["Student_Id"].ToString()

                                  into g

                                  where g.Count() > 0

                                  select a).CopyToDataTable();

            return dtMerged;

   }