Question

我在 MySQL 有四张桌子

< 强 > USERS < /强 >

""https://i.sstatic.net/a1YDx.png" alt="此处输入图像描述"/ >

<强度>USER_INFO

""https://i.sstatic.net/AM2aR.png" alt="此处输入图像描述"/ >

< 强度> USER_Rights

""https://i.sstatic.net/Mu6th.png" alt="此处输入图像描述"/"

<强 > 101 =右

<% 1> > 102 =书写权

<强 > 103 =删除右

< 强 > GROUPS

""https://i.sstatic.net/oryUX.png" alt="此处的内置图像描述"/ >

现在,当我想选择所有用户使用 InNER JOIN 时,我做类似的事情

SELECT users.id, user_info.first_name, user_info.last_name, user_rights.right
    FROM `users`
INNER 
    JOIN user_info 
    ON users.id = user_info.user_id
ORDER BY user_info.first_name;

我有两个用户。

我想再做一个INNER JOIN 来选择第1组中拥有权利的成员,

SELECT users.id, user_info.first_name, user_info.last_name, user_rights.right
    FROM `users`
INNER 
    JOIN user_info 
    ON users.id = user_info.user_id
INNER 
    JOIN user_rights 
    ON user_rights.rights =  101  
ORDER BY user_info.first_name;

想法是在某个群体中选择什么成员拥有READ权利。希望我能够清楚说明这一点。

Answer 1

使用左加入用户- 权利来获取所有用户和权利

SELECT users.id, 
       user_info.first_name, 
       user_info.last_name, 
       user_rights.right 
FROM   users 
       INNER JOIN user_info 
         ON users.id = user_info.user_id 
       LEFT JOIN user_rights 
         ON user_rights.user_id = users.id 
            AND user_rights.right =  101  
       LEFT JOIN GROUPS 
         ON user_rights.group = GROUPS.group 
            AND groups.group_name =  Human Resources  
ORDER  BY user_info.first_name;

Answer 2

SELECT users.id, user_info.first_name, user_info.last_name, user_rights.right
    FROM `users`
INNER 
    JOIN user_info 
    ON users.id = user_info.user_id
INNER 
    JOIN user_rights 
    ON user_rights.user_id = users.id 
INNER JOIN groups 
    on groups.id = user_rights.group
where user_rights.right =  101  
and groups.group_name =  Human Resources 
ORDER BY user_info.first_name;

Answer 3

您必须添加组合表格的连结 :

SELECT users.id, user_info.first_name, user_info.last_name, user_rights.right
    FROM `users`
INNER 
    JOIN user_info 
    ON users.id = user_info.user_id
INNER 
    JOIN user_rights 
    ON user_rights.user_id = users.id
INNER 
    JOIN groups 
    ON user_rights.group = groups.id
WHERE user_rights.rights =  101  AND groups.group_name =  Human Resources

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