How can I rollback an UPDATE query in SQL server 2005?

Question

How can I rollback an UPDATE query in SQL server 2005?

I need to do this in SQL, not through code.

Answer 1

in this example we run 2 line insert into query and if all of them true it run but if not no run anything and ROLLBACK

DECLARE @rowcount int  set @rowcount = 0 ; 
BEGIN TRANSACTION [Tran1]
BEGIN TRY 
 insert into [database].[dbo].[tbl1] (fld1) values('1') ;
    set @rowcount = (@rowcount + @@ROWCOUNT); 
 insert into [database].[dbo].[tbl2] (fld1) values('2') ;
    set @rowcount = (@rowcount + @@ROWCOUNT); 

IF @rowcount =  2
  COMMIT TRANSACTION[Tran1]
ELSE
  ROLLBACK TRANSACTION[Tran1]
END TRY
  BEGIN CATCH
  ROLLBACK TRANSACTION[Tran1]
END CATCH