| -- | |
| -- Create new table t | |
| -- | |
| CREATE TEMPORARY TABLE t(pid INT, wid INT, state CHARACTER VARYING(30)); | |
| -- | |
| -- Insert a row and keep state as empty | |
| -- | |
| INSERT INTO t VALUES(1, 1); | |
| -- | |
| -- use nested decode | |
| -- | |
| SELECT DECODE(DECODE(state, '', NULL, state), '-', NULL, state) AS state FROM t; |