求sql触发器语句

users表
name  companyId  companyName


company表
companyId  companyName
1          a公司
2          b公司

当添加user表时,跟据所填的users.comapnyId,用触发器产生users.companyName对应的company表的companyName值

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select companyName from company where companyId =@companyId 

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SQL code:
create trigger tri_users_insert
on users
instead of insert
as
begin
insert users
select i.name,i.companyId,c.companyName
from inserted i,company c
where i.companyId=c.companyId
end

或者不用instead of，插入后用触发器进行更新

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SQL code:
create trigger tri_users_insert
on users
after insert
as
begin
update u
set u.companyName=c.companyName
from users u,inserted i,company c
where i.companyId=c.companyId and i.companyId=u.companyId
end

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支持

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学习

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最后不要用触发器了,用外键关联,手动添加.方便实用,维护也很好