SQL-一對多並獲得所有沒有的用戶

Question

我有用戶和權限表。 它們之間的關系是：

一位用戶有HAS MANY權限。

我需要讓所有沒有權限的用戶都hide 。

例如，用戶表具有：

 id ¦ name   ¦ email           ¦ password  
 ---+ -------+-----------------+---------- 
  1 ¦ Test 1 ¦ test@gmail.com  ¦ 1234      
  2 ¦ Test 2 ¦ test2@gmail.com ¦ 2345      
  3 ¦ Test 3 ¦ test3@gmail.com ¦ 2345  
  4 ¦ Test 4 ¦ test4@gmail.com ¦ 8888
  5 ¦ Test 5 ¦ test5@gmail.com ¦ 9876  

---

和權限表如下所示：

   user_id ¦ permission  
  ---------+------------ 
   1       ¦ read        
   2       ¦ edit        
   2       ¦ hide     
   4       ¦ edit   
   5       ¦ hide        

這是我到目前為止嘗試過的：

SELECT * 
FROM users 
  LEFT JOIN permissions 
         ON users.id = permissions.user_id 
        AND permissions.permission != 'hide'

但這仍然讓我成為第二用戶，因為第二用戶也具有權限編輯。

預期結果：

 id ¦ name   ¦ email           ¦ password  ¦ permission 
 ---+ -------+-----------------+---------- +------------
  1 ¦ Test 1 ¦ test@gmail.com  ¦ 1234      ¦ read      
  3 ¦ Test 3 ¦ test3@gmail.com ¦ 2345      ¦ null      
  4 ¦ Test 4 ¦ test4@gmail.com ¦ 8888      ¦ edit         

最好的方法是什么？

Answer 1

not exists好理由

SELECT * 
FROM users u
left JOIN permissions p
  ON u.id = p.user_id 
where not exists ( select 1 
                   from permissions p2
                   where p2.user_id = u.id 
                   and p2.permission = 'hide'
                 )

Answer 2

SELECT * 
FROM users u
left JOIN permissions p
  ON u.id = p.id 
where u.id not in 
( 
  select id
  from permissions
  where permission = 'hide'
  group by id
)

輸出

id  Name    Email   Password        id       permission
1   Test 1  test@gmail.com  1234    1        read
3   Test 3  test3@gmail.com 2345    (null)   (null)

Answer 3

一個可能的答案可能是

select * from Users U
inner join Permissions P on P.id=U.id 
WHere U.id NOT IN (SELECT U.ID FROM  Users U
inner join Permissions P on P.id=U.id 
WHere P.Permission ='HIDE')

1）這將返回具有隱藏權限的ID

SELECT U.ID FROM  Users U
inner join Permissions P on P.id=U.id 
WHere P.Permission ='HIDE'

2）這將返回除上述返回的ID之外的所有數據，這將是您期望的

select * from Users U
inner join Permissions P on P.id=U.id 
WHere  U.id NOT IN (SELECT U.ID FROM  Users U
inner join Permissions P on P.id=U.id 
WHere P.Permission ='HIDE')