论述题目：1.、event_table、event varchar2、30、time date、A:create or replace trigger tr_shutdownbefore shutdown on databasebegininsert into event_table values(ora_sysevent,sysdate);end;2. create or replace trigger tr_check_salbefore update of sal on scott.empfor each rowwhen (new.sal1.2*old.sal)beginraise_application_error(-20931,、20%);end; 、 update emp set sal=sal*1.25 empno=7788、A:、20%、20%3. 、before、emp、sal、,、A:create or replace trriger tr_emp_salbefore update of sal on empfor each rowbeginif:new.salDECLARE2 v1 NUMBER;3 v2 NUMBER;4 BEGIN5 v1:=round(6 v2:=trunc(7 dbms_output.put_line(、|v1);8 dbms_output.put_line(、:|v2);9 END;10 /30. 、PL/SQL、SQL*Plus、DBMS_OUTPUT、string、hello world、HELLO WORLD、Hello WorldASQL DECLARE2 v1 varchar2(100);3 v2 varchar2(100);4 BEGIN5 v1:=upper(6 v2:=initcap(7 dbms_output.put_line(、:|v1);8 dbms_output.put_line(、:|v2);9 END;31. 、Aselect group#,sequence#,members,bytes,status,archived from v$log;32. 、system、sys、d:disk5redo01b.log、d:disk5redo02b.log、d:disk5redo03b.logAalter database add logfile memberd:disk5redo01b.logto group 1,d:disk5redo02b.logto group 2,d:disk5redo03b.logto group 3;33.