orcale update join

 1 UPDATE WATCHER_TASK a 
 2 SET a.LAST_MODIFIER_ID = (
 3     SELECT
 4         b.USER_ID 
 5     FROM
 6         task_user b 
 7     WHERE
 8         a.TASK_ID = b.TASK_ID 
 9         AND b.TASK_TYPE = 3 
10         AND b.USER_IDENTITY = 1 
11         AND b.DEL_FLAG = 0 
12     ) 
13 WHERE
14     a.DEL_FLAG = 0