Question

I need to update a record IFF there is only one record matching my search criteria. Here’s what I have, but it’s crude:

DECLARE @TestCount INT;

SELECT @TestCount = COUNT(*)
FROM TestRecords tr
WHERE
    tr.UnitSerial = @UnitSerial
      AND
    tr.PassFailStatus = 1;

IF (@TestCount = 1)
UPDATE
    TestRecords
SET
    Invalid = 1
WHERE
    TestRecordID = 
           (SELECT TestRecordID
            FROM TestRecords tr
            WHERE
            tr.UnitSerial = @UnitSerial
              AND
            tr.PassFailStatus = 1);

Of course this is example code – there are more restrictions and tables joins, etc in the SELECT statement, and it’s all wrapped by a transaction, but this is the gist of the stored proc logic.

I’m thinking there has to be a better way but I don’t know what that is. Any suggestions?

Thanks, Dave

Answer 1

You could do it in one query as:

with toupdate as (
     select tr.*,
            count(*) over () as cnt
     from TestRecords tr
     where tr.UnitSerial = @UnitSerial AND tr.PassFailStatus = 1
    )
update toupdate
    set Invalid = 1
    where cnt = 1

This assumes you are using SQL 2005 or greater.