SQL> SELECT s1.username || '@' || s1.machine|| ' ( SID=' || s1.sid || ' ) is blocking '|| s2.username || '@' || s2.machine || ' ( SID=' || s2.sid || ' ) ' AS blocking_status, s1.SQL_ID FROM v$lock l1, v$session s1, v$lock l2, v$session s2 WHERE s1.sid=l1.sid AND s2.sid=l2.sid AND l1.BLOCK=1 AND l2.request > 0 AND l1.id1 = l2.id1 AND l2.id2 = l2.id2;