10일 20일 30일 1 SLEEP20 2 2 dbms_pipe.receive_me 3 OR 1 4 WAITFOR 2 5 1 4 6 PG_SLEEP20 1 7 dbms_pipe.receive_messagea20 3 1 1 2 SLEEP20 3 OR 4 WAITFOR 5 dbms_pipe.receive_me 6 PG_SLEEP20 7 dbms_pipe.receive_messagea20 1 1 2 SLEEP20 3 OR 4 WAITFOR 5 dbms_pipe.receive_me 6 PG_SLEEP20 7 dbms_pipe.receive_messagea20 11위 - 20위