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