Nested case

Question

SEELCT ........FROM ............WHERE
SUB_CLASS_CD = (CASE
WHEN CUR_VAR.CLASS_CD = 11 THEN
(CASE WHEN CUR_VAR.SUB_CLASS_CD = 17
*CUR_VAR.SUB_CLASS_CD
ELSE NULL
END)
WHEN CUR_VAR.CLAS_CD = 60 AND CUR_VAR.SUB_CLASS_CD IN (20,42,62,83,88,89,91,92) THEN
CUR_VAR.SUB_CLASS_CD
WHEN CUR_VAR.CLASS_CD = 70 THEN
CASE WHEN CUR_VAR.SUB_CLASS_CD = 83
CUR_VAR.SUB_CLASS_CD
ELSE NULL
END
ELSE CUR_VAR.SUB_CLASS_CD
END)
This is showing error message i.e. keyword missing at * marked place.
Can any body suggest me?
thanks in advance.

Answer 1

Hi,
As SBH said, you left out the THEN keyword. The same thing happened in the 2nd nested CASE.
Always indent your code to show the structure of long expressions like this:
SUB_CLASS_CD = ( CASE
                       WHEN  CUR_VAR.CLASS_CD = 11
                THEN  ( CASE
                                WHEN  CUR_VAR.SUB_CLASS_CD = 17
                       THEN      CUR_VAR.SUB_CLASS_CD
                             ELSE  NULL
                     END
                WHEN  CUR_VAR.CLAS_CD = 60          -- Not class_cd (with 2 s's)?
                AND   CUR_VAR.SUB_CLASS_CD IN (20,42,62,83,88,89,91,92)
                THEN  CUR_VAR.SUB_CLASS_CD
                WHEN  CUR_VAR.CLASS_CD = 70
                THEN  CASE
                               WHEN  CUR_VAR.SUB_CLASS_CD = 83
                     THEN  CUR_VAR.SUB_CLASS_CD   -- THEN needed here, too
                     ELSE  NULL
                   END
               ELSE  CUR_VAR.SUB_CLASS_CD
          END
           )You can get the same results without nested CASE:
sub_class_cd = CASE
             WHEN  class_cd = 11 AND sub_class_cd     = 17     THEN  sub_class_cd
             WHEN  class_cd = 11                         THEN  NULL
             WHEN  class_cd = 70 AND sub_class_cd = 83     THEN  sub_class_cd
             WHEN      class_cd = 70                          THEN  NULL
                                                ELSE  sub_class_cd
            ENDThe test for class_cd = 60 (or clas_cd = 60) wasn't doing anything, so I removed it. If class_cd = 60, but sub_class_cd is in the list of special values, then sub_class_cd is returned by the THEN clause in the middle. If class_cd = 60, but sub_class_cd is not in the list of special values, then sub_class_cd is returned by the THEN clause at the end. Either way, sub_class_cd is returned, so why not do it just once, at the end?
You can also get the same results without CASE:
WHERE   (     class_cd     = 11
     AND  sub_class_cd != 17
OR        (     class_cd     = 70
     AND  sub_class_cd != 83
OR     class_cd     NOT IN (11, 70)