Find a record that doesnt exist and display a message

Question

When I run the following query why wont it display the word 'FAIL'.
SELECT
  CASE
    WHEN table_name IN('DBA_OBJECTS') THEN 'PASS'
    ELSE 'FAIL'
  END TABLE_EXISTS
FROM dictionary
WHERE table_name = 'DBA_OBJECT'
;Ben

Answer 1

Hi Benton,
The query filter (WHERE table_name = 'DBA_OBJECT') cause zero record to be returned.
To trick you can use aggregate function which always return single record even if record is found or not. If no record is found then NULL is returned.
SQL> SELECT CASE WHEN MAX(table_name) IN('DBA_OBJECTS') THEN 'PASS' ELSE 'FAIL' END TABLE_EXISTS -- OR NVL2(MAX(table_name),'PASS','FAIL') TABLE_EXISTS
  2  FROM dictionary
  3  WHERE table_name = 'DBA_OBJECT'
  4  AND ROWNUM = 1
  5  /
TABLE_EXISTS
FAIL
{code}