Question

How can detect an updated value in a Trigger specially in SQL Server 2005?

Answer 1

I found this answer true !!
An UPDATE trigger is used to perform an action after an update is made on a table.

CREATE TRIGGER tr_Orders_UPDATE
ON Orders
AFTER UPDATE
AS

--Make sure Priority was changed
IF NOT UPDATE(Ord_Priority)
RETURN

--Determine if Priority was changed to high
IF EXISTS (SELECT *
       FROM INSERTED a
   JOIN DELETED b ON a.Ord_ID=b.Ord_ID
   WHERE b.Ord_Priority <> 'High' AND
   a.Ord_Priority = 'High')
BEGIN
DECLARE @Count tinyint
SET @Count = (SELECT COUNT(*)
            FROM INSERTED a
    JOIN DELETED b ON a.Ord_ID=b.Ord_ID
    WHERE b.Ord_Priority <> 'High' AND
    a.Ord_Priority = 'High')
PRINT CAST(@Count as varchar(3))+' row(s) where changed to a priority of High'
END
go

In Part I the INSERT trigger watched for orders with a priority of ‘High.’ The UPDATE trigger watches for orders whose priority are changed from something else to High.

The IF statement checks to see if the Ord_Priority value was changed. If not we can save some time by exiting the trigger immediately.

The deleted table holds the pre-UPDATE values and inserted table holds the new values. When the tables are joined it is easy to tell when the priority changes from something else to High.

Reference