A Interview question How to determine what value you have updated of a column ? A output clause example #TIP 48

 

Problem:-

Sometimes it may require that whatever you have updated you want to know what was the previous value of that column?

It was asked by many interviewer in the interview how to avoid trigger or how to know what was previous value before update ?

Solution:-

Now to achieve this the basic step is before updating the record select those value and have it in a temporary variable.

But We are doing here by a new feature (not exactly new introduced in SQL Server 2005) which is OUTPUT CLAUSE

Suppose I have tbluser table in which a user record with id 1 having userame “staff”

Now I have to update this in capital letter. To achieve this we have to write following query

UPDATE tblUser
SET UserName = 'STAFF'
OUTPUT INSERTED.UserName,
   deleted.UserName
WHERE userId= 1
   

When you run it you will get output as shown below

 

I hope it may helpful you somewhere enjoy !!!

RJ!!!