oracle 插删改 触发器

Question

create or replace trigger TG_attend_417
after insert or delete or update on attend_417
for each row
begin
if inserting then
if :new.attendance = 'la' then update stud_417 set sum_evaluation = sum_evaluation-2;

elsif :new.attendance = 't' then update stud_417 set sum_evaluation = sum_evaluation-5;
else :new.attendance = 'le' then update stud_417 set sum_evaluation = sum_evaluation-1;
end if;
end if;
if deleting then
if :old.attendance = 'la' then update stud_417 set sum_evaluation = sum_evaluation+2;
elsif :old.attendance = 't' then update stud_417 set sum_evaluation = sum_evaluation+5;
else :old.attendance = 'le' then update stud_417 set sum_evaluation = sum_evaluation+1;
end if;
end if;
if updating then
if :new.attendance = 'la' then update stud_417 set sum_evaluation = sum_evaluation-2;
elsif :new.attendance = 't' then update stud_417 set sum_evaluation = sum_evaluation-5;
else :new.attendance = 'le' then update stud_417 set sum_evaluation = sum_evaluation-1;
end if;
end if;
end;
.
/
show errors;

请问哪里错了？