Question

我有以下SQL查询：

SELECT users.user_id,
       users.first_name,
       users.last_name,
       roles.role,
       roles.role_id,
       users.username,
       users.description,
       users_vs_teams.team_id,
       teams.team_name,
       teams.status
FROM users
     INNER JOIN roles ON users.role_id = roles.role_id
     INNER JOIN users_vs_teams ON users.user_id = users_vs_teams.user_id
     INNER JOIN teams ON users_vs_teams.team_id = teams.team_id
WHERE( users.role_id = 3 )

此查询显示用户角色为3的所有用户以及由于他们user_id出现在users_vs_teams表中而被分配给sprint的团队。但是，我希望显示与此相反的位置，它显示角色为3但在user_id表中找不到users_vs_teams的用户。

非常感谢任何帮助。

Answer 1

SELECT  users.user_id, 
        users.first_name, 
        users.last_name, 
        roles.role, 
        roles.role_id, 
        users.username, 
        users.description
FROM    users 
        INNER JOIN roles ON users.role_id = roles.role_id 
        LEFT JOIN users_vs_teams ON users.user_id = users_vs_teams.user_id 
WHERE   users.role_id = 3 
        AND  users_vs_teams.user_id IS NULL

Answer 2

 SELECT users.user_id, users.first_name, users.last_name, roles.role, roles.role_id, users.username, users.description, users_vs_teams.team_id, teams.team_name, teams.status
 FROM users INNER JOIN roles ON users.role_id = roles.role_id 
            INNER JOIN users_vs_teams ON users.user_id <> users_vs_teams.user_id 
            INNER JOIN teams ON users_vs_teams.team_id = teams.team_id
 WHERE (users.role_id = 3)

Answer 3

更改为左外连接并向where子句添加另一个条件。左外连接从左侧的表（此处为用户）中提取所有行，并且条件确保只有那些行出现在右侧表中没有合适匹配的位置（此处为users_vs_teams）。在以下查询中，您必须更改＆＃34; pk＆＃34;在附加的where子句条件中，实际列是users_vs_teams表的主键。

SELECT  users.user_id, users.first_name, users.last_name, roles.role, roles.role_id, users.username, users.description, users_vs_teams.team_id, teams.team_name, teams.status
FROM    users 
        INNER JOIN roles ON users.role_id = roles.role_id 
        INNER JOIN teams ON users_vs_teams.team_id = teams.team_id
        LEFT OUTER JOIN users_vs_teams ON users.user_id = users_vs_teams.user_id 
WHERE   (users.role_id = 3)
        AND users_vs_teams.pk IS NULL

Answer 4

使用LEFT JOIN代替NULL表中的所有users_vs_teams个ID，在AND users_vs_teams.user_id IS NULL子句中添加WHERE，您可以得到你想要的东西。

 SELECT users.user_id,
        users.first_name,
        users.last_name,
        roles.role,
        roles.role_id,
        users.username,
        users.description,
        users_vs_teams.team_id,
        teams.team_name,
        teams.status
    FROM users
        INNER JOIN roles ON users.role_id = roles.role_id
        INNER JOIN teams ON users_vs_teams.team_id = teams.team_id
        LEFT JOIN users_vs_teams ON users.user_id = users_vs_teams.user_id
    WHERE( users.role_id = 3 )
    AND users_vs_teams.user_id IS NULL

选择Command Where Users ID未出现在另一个表中

4 个答案: