Question

I’m trying to create a T-SQL query for several hours now. Google and the forum search did not help, so I hope someone can help me with this.

There are two tables, Change and Journal. Each row in Change has 5 related rows in Journal.

What I want to do is to copy the column value (CreatedDateTime) of a specific related row from Journal into the column AuthorizationDate of Change. This should be done for all rows in Change.

This is what I’ve achieved so far:

UPDATE Change 
SET Change.ap_ITSM_MDP_AuthorizationDate = 
    ( SELECT Journal.CreatedDateTime 
      FROM Journal 
        JOIN Change 
          ON Journal.Parentlink_RecID = Change.RecID 
      WHERE ITSM_ChangeNotes_Subject = 'Status changed to: Authorized' 
        AND Change.RecID = Journal.ParentLink_RecID
    )

Unfortunately, I get the following error message:

Msg 512, Level 16, State 1, Line 1
Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.
The statement has been terminated.

I thought I DID limit the result to one by the WHERE clause (ChangeNotes_Subject = '...'). What did I do wrong?

Answer 1

I think this will work:

UPDATE Change 
SET Change.ap_ITSM_MDP_AuthorizationDate = 
    ( SELECT Journal.CreatedDateTime 
      FROM Journal 
      WHERE ITSM_ChangeNotes_Subject = 'Status changed to: Authorized' 
        AND Change.RecID = Journal.ParentLink_RecID
    ) ;

But using JOIN is better – to avoid any unwanted updates. Here’s how:

UPDATE Change 
SET Change.ap_ITSM_MDP_AuthorizationDate = Journal.CreatedDateTime 
FROM Journal 
  JOIN Change 
    ON Change.RecID = Journal.ParentLink_RecID
WHERE ITSM_ChangeNotes_Subject = 'Status changed to: Authorized' ;