Question

我正在尝试加入一些表来接收一些数据，但它没有按预期工作。这是我的疑问：

SELECT USR.PK_User AS PKUser
    ,USR.NAME AS NAME
FROM [User] USR
LEFT JOIN aspnet_Users ASPU ON USR.NAME = ASPU.UserName
LEFT JOIN aspnet_UsersInRoles ASPUIR ON ASPU.UserId = ASPUIR.UserId
WHERE ASPUIR.RoleId = 'E8700479-902A-42F1-A500-4FA02CAC356C'

此查询未返回任何内容。但如果我这样做：

SELECT * FROM [aspnet_UsersInRoles] WHERE RoleId = 'E8700479-902A-42F1-A500-4FA02CAC356C'

我获得76个选定的行。如果我这样做：

SELECT USR.PK_User AS PKUser
    ,USR.NAME AS NAME
FROM [User] USR
LEFT JOIN aspnet_Users ASPU ON USR.NAME = ASPU.UserName
LEFT JOIN aspnet_UsersInRoles ASPUIR ON ASPU.UserId = ASPUIR.UserId

我得到了返回的预期行。另外，如果我添加：

WHERE ASPUIR.RoleId IS NULL

我回来了。

我做错了什么？

Answer 1

您需要ON中的条件而不是WHERE。

否则你只需要有效地恢复内部联接。

SELECT USR.PK_User AS PKUser,
       USR.NAME    AS NAME
FROM   [User] USR
       LEFT JOIN aspnet_Users ASPU
         ON USR.NAME = ASPU.UserName
       LEFT JOIN aspnet_UsersInRoles ASPUIR
         ON ASPU.UserId = ASPUIR.UserId
            AND ASPUIR.RoleId = 'E8700479-902A-42F1-A500-4FA02CAC356C'

Answer 2

试试这个： -

SELECT USR.PK_User AS PKUser,
   USR.NAME    AS NAME
FROM   [User] USR
   LEFT JOIN aspnet_Users ASPU
     ON USR.NAME = ASPU.UserName
   LEFT JOIN aspnet_UsersInRoles ASPUIR
     ON ASPU.UserId = ASPUIR.UserId
        AND ASPUIR.RoleId = 'E8700479-902A-42F1-A500-4FA02CAC356C'

WHERE子句无法按预期运行

2 个答案: