Question

I’ve got a table in the following format:

Name    Address1    Address2    Address3
Joe     NULL        1 A Road    London
Bob     2 A Lane    NULL        London

I’d like to run an update to move all the values left where there are nulls so that I end up with:

Name    Address1    Address2    Address3
Joe     1 A Road    London      NULL
Bob     2 A Lane    London      NULL

Please help!

Thanks,
Josh

Answer 1

David’s solution is the most efficient. One that might be more easily extend-able for greater numbers of columns is.

;WITH cte
     AS (SELECT *,
                 MAX(CASE WHEN RN=1 THEN value END) OVER (PARTITION BY ContactId) AS new_Address1,
                 MAX(CASE WHEN RN=2 THEN value END) OVER (PARTITION BY ContactId) AS new_Address2,
                 MAX(CASE WHEN RN=3 THEN value END) OVER (PARTITION BY ContactId) AS new_Address3
         FROM   #Addresses
                OUTER APPLY (SELECT ROW_NUMBER() OVER (ORDER BY CASE WHEN value IS NULL THEN 1 ELSE 0 END, idx) AS
                                   RN, idx, value
                             FROM   (VALUES(1,Address1),
                                           (2,Address2),
                                           (3,Address3)) t (idx, value)) d)
UPDATE cte
SET    Address1 = new_Address1,
       Address2 = new_Address2,
       Address3 = new_Address3