Question

在我之前的问题中，我询问过如何将查询结果存储在变量中...现在我意识到查询可以返回多行。

我目前有这个：

SELECT @UserId = UserId FROM aspnet_Users WHERE UserName = @username

我想做这样的事情：

DELETE FROM some_table WHERE UserId IN ( *the ID list* )
DELETE FROM some_table_2 WHERE UserId IN ( *the ID list* )

我的第一直觉是使用“GROUP_CONCAT”，但显然这是一个仅限MySQL的功能。有一些方法可以提供相同的功能，但我想知道是否有更好的方法来构建查询？

Answer 1

SELECT * FROM dbo.aspnet_UsersInRoles 
WHERE UserId IN ( 
    SELECT UserId FROM aspnet_Users 
    WHERE UserName = @username  
)

Answer 2

这应该这样做..

SELECT 
  * 
FROM 
  dbo.aspnet_UsersInRoles 
WHERE 
  UserId IN ( 
             SELECT 
               UserId 
             FROM 
               aspnet_Users 
             WHERE 
               UserName = @username
       )

Answer 3

delete from st
    from some_table st
        inner join aspnet_Users au
            on st.UserId = au.UserId
    where /* add additional criteria here to produce "* the ID list *" */

Answer 4

如果要避免重复子查询，可以将其结果放入临时表或表变量中。例如：

/*declare and fill a table variable containing all user ids you need to manipulate*/
declare @t table(userid int)
insert into @t(userid) select UserId from aspnet_Users where UserName=@username

/*delete from some table by using the temp variable*/
delete from st 
from some_table st 
    inner join @t t 
        on st.userid = t.userid 
/*repeat this for some other table*/
delete from st 
from some_other_table st 
    inner join @t t 
        on st.userid = t.userid

如果你想避免多个删除语句，如果some_table中不存在some_other_table中的用户id，那么你可以在some_table上创建触发器：

create trigger x on some_table for delete
    as
    begin
     delete from some_other_table 
     where userid in (select userid from deleted)
  end

我可以将多行从存储过程查询传递到另一个查询吗？

4 个答案: