1 删除整张表的数据，并还原自增长值
TRUNCATE TABLE TbWeixinActivity

2 3张表左连接
select a.ID,c.Name,b.nickname,a.CreateDate from TbUserJoin as a left join tbWX_User as b on a.WeChatID=b.openid left join TbUnitActivity as c on a.ActivityID=c.ID where a.IsValid=1 order by a.CreateDate asc //where条件和排序可以根据需求加或不加

3 视图
2 3张表左连接
select a.ID,c.Name,b.nickname,a.CreateDate from TbUserJoin as a
left join tbWX_User as b on a.WeChatID=b.openid
left join TbUnitActivity as c on a.ActivityID=c.ID

4 把表中的数据复制到另一个数据库中
select *
into TbPersonRegister //目标数据库
from [wxlodc20150708].dbo.TbPersonRegister //如果报错，说明目标数据库已经有了这个表，把它删除即可

5 使用触发器进行级连删除
create trigger triggerPersonDelete
on person
instead of DELETE
as
begin
declare @pId int
select @pId=id from deleted
--删除tel
delete Tel where PersonID=@pId
--删除person 主表
delete person where id=@pId
end