before delete 触发器里面不能使用 :new 。create or replace trigger username_tri before insert or delete on username for each row begin if inserting then select username_seq.nextval into :new.userId from dual; elsif deleting then null ; else null ; end if ; end;deleting 里面写你要做的事情。
before insert or delete on username
for each row
begin
if inserting then
select username_seq.nextval into :new.userId from dual;
elsif deleting then
null ;
else
null ;
end if ;
end;deleting 里面写你要做的事情。