Oracle SQL - CASE in a WHERE clause

Is it possible to somehow do this?

WITH T1 AS
(
   SELECT 1 AS SEQ, 'NOTHING 1' AS SOME_TYPE FROM DUAL UNION ALL
   SELECT 2 AS SEQ, 'NOTHING 2' AS SOME_TYPE FROM DUAL UNION ALL
   SELECT 3 AS SEQ, 'SOMETHING 1' AS SOME_TYPE FROM DUAL UNION ALL
   SELECT 4 AS SEQ, 'SOMETHING 2' AS SOME_TYPE FROM DUAL UNION ALL
   SELECT 5 AS SEQ, 'SOMETHING 3' AS SOME_TYPE FROM DUAL UNION ALL
   select 6 as seq, 'SOMETHING 4' AS SOME_TYPE from dual
)
, T2 AS
(
   SELECT 'A' AS COMPARE_TYPE FROM DUAL UNION ALL
   SELECT 'B' AS COMPARE_TYPE FROM DUAL 
)
SELECT T2.*, T1.* 
FROM T1, T2
WHERE  CASE T2.COMPARE_TYPE 
         WHEN 'A'
            THEN T1.SOME_TYPE LIKE 'NOTHING%'
         ELSE T1.SOME_TYPE NOT LIKE 'NOTHING%' 
      END

I know that my WHERE is clause is not correct.

Any help would be great in knowing if this type of statement is possible.

I don't want to write a Dynamic SQL. If I have to I will write 2 different SQL statements.

Thanks

Thanks for posting the sample data. It would also be helpful to describe in words and with actual output what you want to be returned by your query.

I'm guessing that you want something like

SQL> ed
Wrote file afiedt.buf

  1  WITH T1 AS
  2  (
  3  SELECT 1 AS SEQ, 'NOTHING 1' AS SOME_TYPE FROM DUAL UNION ALL
  4  SELECT 2 AS SEQ, 'NOTHING 2' AS SOME_TYPE FROM DUAL UNION ALL
  5  SELECT 3 AS SEQ, 'SOMETHING 1' AS SOME_TYPE FROM DUAL UNION ALL
  6  SELECT 4 AS SEQ, 'SOMETHING 2' AS SOME_TYPE FROM DUAL UNION ALL
  7  SELECT 5 AS SEQ, 'SOMETHING 3' AS SOME_TYPE FROM DUAL UNION ALL
  8  select 6 as seq, 'SOMETHING 4' AS SOME_type from dual
  9  )
 10  , T2 AS
 11  (
 12  SELECT 'A' AS COMPARE_TYPE FROM DUAL UNION ALL
 13  SELECT 'B' AS COMPARE_type FROM DUAL
 14  )
 15  SELECT T2.*, T1.*
 16    FROM T1, T2
 17   WHERE (CASE WHEN T2.COMPARE_TYPE = 'A' AND
 18                    T1.SOME_TYPE LIKE 'NOTHING%'
 19                 THEN 1
 20               WHEN T2.COMPARE_TYPE != 'A' AND
 21                    T1.SOME_TYPE NOT LIKE 'NOTHING%'
 22                 THEN 1
 23               ELSE 0
 24*           END) = 1
SQL> / 

C        SEQ SOME_TYPE
- ---------- -----------
A          1 NOTHING 1
A          2 NOTHING 2
B          3 SOMETHING 1
B          4 SOMETHING 2
B          5 SOMETHING 3
B          6 SOMETHING 4

6 rows selected.

But I'm making a lot of guesses about what your code is supposed to mean.

That this appears to be identical to a question someone asked in the OTN forums. My answer is the same in both places.

StackExchange Database Administrators Q#1170, answer score: 15