create trigger a_tri
before insert on a
for each row
begin
update b set SL=SL+1 where XH=:new.XH;
if sql%rowcount=0 then
insert b values(:new.sl,:new.xh);
end if;
end;
/
create or replace trigger aa
on A before insert
for each row
declare
v_n number;
begin
select count(1) into v_n
from dual
where exists
(select 1 from b where xh=:new.xh)
if v_n > 0 then
update b set sl=sl+:new.sl;
else
insert into b values(:new.xh,:new.sl)
end if;
end;