触发器问题 急!

create trigger delete_A

on 表A for delete
as

if(select count(*) from deleted)>0
delete from 表B where coname = (select coname from deleted)

我要删除A新闻同时删除相关多个评论表B

B表超过2条信息时

出错如下

子查询返回的值多于一个。当子查询跟随在 =、!=、<、<=、>、>= 之后，或子查询用作表达式时，这种情况是不允许的。

请教如何解决

create trigger delete_A

on 表A for delete
as

if(select count(*) from deleted)>0
delete from 表B where coname = (select coname from deleted)

注意看他的提示， 最后的 where coname=(select coname from deleted) 这个的子查询返回的是多个值，所以子查询中加入限制条件，比如 select coname from deleted where id=0 这样才行！