how to use case statement in group by

Question

I have following case statements in my SELECT clause, also I have a group by clause... So, Is it okay to specify UF.CONT_PID & UF.M_STATUS_CD in my GROUP BY Clause ? I need to specify the entire CASE statement in GROUP BY ?

 CASE WHEN UF.CONT_PID IN    
 ('04007005', '01019045','01019046') OR 
 (UF.M_STATUS_CD IN ('01', '02') 
 THEN    
 1    
 ELSE    
0    
 END

Answer 1

I believe you can group by in two ways:

GROUP BY UF.CONT_PID, UF.M_STATUS_CD

OR

GROUP BY CASE WHEN UF.CONT_PID IN ('04007005', '01019045','01019046') OR (UF.M_STATUS_CD IN ('01', '02') THEN 1 ELSE 0 END

But keep in mind that these are very different groupings.

Answer 2

Rather than repeat the expression, you could do:

SELECT col /*, other cols */ FROM
(
  SELECT col = CASE WHEN /*...long-winded expression...*/ 
    THEN 1 ELSE 0 END /*, other cols */
  FROM dbo.table
) AS x
GROUP BY col;