select id from tb1
except
select id from tb2

------解决方案--------------------
SQL code

create view [view_name]
as
select a.id
from 表A a 
left join 表B b on a.id=b.id
where b.id is null

------解决方案--------------------
SQL code
create tigger test on a
for delete
as
begin
delete from b where exists(select 1 from instered where id=b.id)
end

------解决方案--------------------
探讨

追问一下，如果两表都包含1，2，3，如果表A删除了2，我想建立一个trigger，让表B也自动删除2，应该怎么做呢