--创建触发器及作用举例

create or replace trigger tri

before delete on emp

--在删除emp表数据之前需要做的事根据自己的业务去写，before是在之前做的事，after是在之后要做的事

declare

t_result number := 10;

begin

  dbms_output.put_line('admin' || t_result);

end tri;

--下面是对表某些字段进行更新之后做的操作

create or replace trigger TRI_DISPLAYTABLE

after update of datatype,dbcolumnname,name on P#GCFR_T_FACTOR

for each row

declare

errno number;

errmsg varchar2(30);

begin

if updating ('datatype') then

update GCFR_T_DISPLAYTABLE t set t.datatype = :new.datatype where t.viewname = :old.dbtablename

and t.isvirtualcolumn = 0 and t.columncode = :old.dbcolumnname;

end if;

if updating ('dbcolumnname') then

update GCFR_T_DISPLAYTABLE t set t.datatype = :new.datatype where t.viewname = :old.dbtablename

and t.isvirtualcolumn = 0 and t.columncode = :old.dbcolumnname;

end if;

if updating ('name') then

update GCFR_T_DISPLAYTABLE t set t.datatype = :new.datatype where t.viewname = :old.dbtablename

and t.isvirtualcolumn = 0 and t.columncode = :old.dbcolumnname;

end if;

end;

--删除触发器

drop trigger tri;