Question

我需要输入姓名和主管姓名

表名：用户

id | name |
-----------
 1 | David 
 2 | Frank
 3 | Shane
 4 | Franchich

另一个表格名称：详细信息

user_id | supervisor_id|
----------------------------
  1 | 4
  2 | 3
  3 | 4

我尝试过：

select 
    name as user name 
from user, details 
WHERE details.user_id=user.id

但失败

现在我想得到类似的结果

User Name | Supervisor Name
------------------------------
David | Franchich
Frank | Shane
Shane | Franchich

那怎么可能？

Answer 1

您要在表详细信息和表用户之间寻找两个JOIN，例如：

select
    u1.name as user_name,
    u2.name as supervisor_name
from details d
inner  join user u1 on u1.id = d.user_id
inner  join user u2 on u2.id = d.supervisor_id

Answer 2

您应该两次加入user表。您需要表别名来将user标识为“用户”（u），将user标识为“管理者”（m）：

select 
     u.name as UserName, m.username as SupervisorName
from 
     user u
inner join 
     details   on u.id = details.user_id
inner join 
     user m    on details.supervisor_id = m.id

我需要有关mysql查询的帮助

2 个答案: