Question

I have the following SQL within a stored procedure. Is there a way to remove the IF statement and pass the ‘ASC’/’DESC’ option as a variable?

I know I could do the query a number of different ways, or return a table and sort it externally etc. I would just like to know if I can avoid duplicating the CASE statement.

IF @sortOrder = 'Desc'   BEGIN     SELECT * FROM #t_results     ORDER BY     CASE WHEN @OrderBy = 'surname'           THEN surname END DESC,     CASE WHEN @OrderBy = 'forename'          THEN forename END DESC,     CASE WHEN @OrderBy = 'fullName'          THEN fullName END DESC,     CASE WHEN @OrderBy = 'userId'            THEN userId END DESC,     CASE WHEN @OrderBy = 'MobileNumber'      THEN MSISDN END DESC,     CASE WHEN @OrderBy = 'DeviceStatus'      THEN DeviceStatus END DESC,     CASE WHEN @OrderBy = 'LastPosition'      THEN LastPosition END DESC,     CASE WHEN @OrderBy = 'LastAlert'         THEN LastAlert END DESC,     CASE WHEN @OrderBy = 'LastCommunication' THEN LastCommunication END DESC,     CASE WHEN @OrderBy = 'LastPreAlert'      THEN LastPreAlert END DESC      END  ELSE    BEGIN     SELECT * FROM #t_results     ORDER BY     CASE WHEN @OrderBy = 'surname'           THEN surname END DESC,     CASE WHEN @OrderBy = 'forename'          THEN forename END DESC,     CASE WHEN @OrderBy = 'fullName'          THEN fullName END DESC,     CASE WHEN @OrderBy = 'userId'            THEN userId END DESC,     CASE WHEN @OrderBy = 'MobileNumber'      THEN MSISDN END DESC,     CASE WHEN @OrderBy = 'DeviceStatus'      THEN DeviceStatus END DESC,     CASE WHEN @OrderBy = 'LastPosition'      THEN LastPosition END DESC,     CASE WHEN @OrderBy = 'LastAlert'         THEN LastAlert END DESC,     CASE WHEN @OrderBy = 'LastCommunication' THEN LastCommunication END DESC,     CASE WHEN @OrderBy = 'LastPreAlert'      THEN LastPreAlert END DESC      END END 

Answer 1

Pass in @OrderBy int, where positive is ASC, negative is DESC, and the actual number is the column to sort by:

SELECT     dt.yourColumn1         ,dt.yourColumn2         ,dt.yourColumn3         ,CASE              WHEN @OrderBy>0 THEN dt.SortBy             ELSE NULL          END AS SortByAsc         ,CASE              WHEN @OrderBy<0 THEN dt.SortBy             ELSE NULL          END AS SortByDesc     FROM (SELECT               yourColumn1                   ,yourColumn2                   ,yourColumn3                   ,CASE                       WHEN ABS(@OrderBy) = 1 THEN surname                       WHEN ABS(@OrderBy) = 2 THEN forename                       WHEN ABS(@OrderBy) = 3 THEN fullName                       WHEN ABS(@OrderBy) = 4 THEN CONVERT(varchar(10),userId)                       WHEN ABS(@OrderBy) = 5 THEN CONVERT(varchar(10),MobileNumber                       WHEN ABS(@OrderBy) = 6 THEN DeviceStatus                       WHEN ABS(@OrderBy) = 7 THEN LastPosition                       WHEN ABS(@OrderBy) = 8 THEN CONVERT(varchar(23),LastAlert,121)                       WHEN ABS(@OrderBy) = 9 THEN CONVERT(varchar(23),LastCommunication,121)                       WHEN ABS(@OrderBy) =10 THEN CONVERT(varchar(23),LastPreAlert,121)                       ELSE NULL                   END AS SortBy               FROM YourTablesHere               WHERE X=Y          ) dt     ORDER BY SortByAsc ASC, SortByDesc DESC 

Just make sure you build a string that sort properly. Notice I used ‘YYYY-MM-DD hh:mm:ss.mmm’ for the dates and put the numbers into strings. We usually put multiple columns together, so if you sort by surname, forename is used too, etc. Watch out, if you do combine multiple columns you’ll need to pad with zeros or spaces.

If you don’t want the SortByAsc and SortByDesc columns to be in the result set, wrap the entire thing in a derived table.