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