Using Cursor in Sql server

A cursor is a set of rows together with a pointer that identifies a current row.

In other word, Cursor is a database object used by applications to manipulate data in a set on a row-by-row basis, it's like recordset in C#.

Here is the syntax with explanation..
     DECLARE @fName varchar(50), @lName varchar(50)

 
DECLARE cursorName CURSOR -- Declare cursor

LOCAL SCROLL STATIC
 
FOR
 
Select firstName, lastName FROM myTable
 
OPEN cursorName -- open the cursor

FETCH NEXT FROM cursorName
 
   INTO @fName, @lName
 
   PRINT @fName + ' ' + @lName -- print the name

WHILE @@FETCH_STATUS = 0
 
BEGIN
 
   FETCH NEXT FROM cursorName
 
   INTO @fName, @lName
 
   PRINT @fName + ' ' + @lName -- print the name

END
 
CLOSE cursorName -- close the cursor

DEALLOCATE cursorName -- Deallocate the cursor

Example

BEGIN
  declare @EmpName as varchar(20)
  declare @WorkDAte as varchar(50)

  declare  _cur1 cursor for
  select distinct WorkDate from EMP_Attendance where FileName=@FileName
  --select PunchCardNo from EmployeeInfo where PunchCardNo not in (select PunchCardNo from EMP_Attendance where ) and PunchCardNo<>''

  open  _cur1;

  fetch next from _cur1 into @WorkDAte
  --print @WorkDAte

   WHILE @@FETCH_STATUS = 0
   BEGIN
    declare  _cur cursor for
    --select WorkDate from EMP_Attendance where FileName=@FileName
    select EmpName from EmployeeInfo where EmpName not in (select EmpName from EMP_Attendance where WorkDate=@WorkDAte) and EmpName<>''
    --print PunchCardNo
    open  _cur
    fetch next from _cur into @EmpName
    WHILE @@FETCH_STATUS = 0
    --print @PunchCardNo
     BEGIN
      insert into EMP_Attendance( EmpName, WorkDate, StartTime, EndTime, CreatedBy, CreatedDate, UpdatedBy, UpdatedDate, SummaryId, WorkingTime, latetime, Remarks,FileName )
            Select top 1 @EmpName, @WorkDAte, '0', '0', '', '', '', '',3, '', '', '',@FileName  from dbo. EMP_Attendance e
      where e.EmpName= (select top 1 EmpName from EmployeeInfo where EmpCode='GB0197')

      fetch next from _cur into @EmpName
     END
     DEALLOCATE _cur;
    -- CLOSE  _cur;

    --PRINT @WorkDAte

    fetch next from _cur1 into @WorkDAte
  
   END
   DEALLOCATE _cur1;
   --CLOSE  _cur1;  
 END

HERE is an important link : Comparing time interval