MySQL使用相同的外表查询两个不同的列

Question

我正在努力进行SQL查询。

我确实需要知道网络，cidr，vrfold（id，名称和主干）和vrfnew（id，name和backbone）。

也许有人可以提供帮助。

networks
+-----------------+---------------+------+-----+---------+----------------+
| Field           | Type          | Null | Key | Default | Extra          |
+-----------------+---------------+------+-----+---------+----------------+
| id              | int(11)       | NO   | PRI | NULL    | auto_increment |
| network         | varbinary(16) | NO   |     | NULL    |                |
| cidr            | int(11)       | NO   |     | NULL    |                |
| vrfnew_id       | int(11)       | YES  | MUL | NULL    |                |
| vrfold_id       | int(11)       | NO   | MUL | NULL    |                |
| vlan            | varchar(45)   | YES  |     | NULL    |                |
+-----------------+---------------+------+-----+---------+----------------+

vrfs
+--------------+-------------+------+-----+---------+----------------+
| Field        | Type        | Null | Key | Default | Extra          |
+--------------+-------------+------+-----+---------+----------------+
| id           | int(11)     | NO   | PRI | NULL    | auto_increment |
| name         | varchar(45) | NO   |     | NULL    |                |
| backbones_id | int(11)     | NO   | MUL | NULL    |                |
+--------------+-------------+------+-----+---------+----------------+

backbones
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | int(11)     | NO   | PRI | NULL    | auto_increment |
| name  | varchar(25) | NO   |     | NULL    |                |
+-------+-------------+------+-----+---------+----------------+

Answer 1

试试这个：

SELECT A.network, 
       A.cidr, 
       A.vrfold_id, 
       B.name as vrfold_name, 
       C.name as vrfold_backbone_name, 
       A.vrfnew_id, 
       D.name as vrfnew_name, 
       E.name as vrfnew_backbone_name
FROM networks A
JOIN vrfs B on A.vrfold_id = B.id
JOIN backbones C on B.backbones_id = C.id
JOIN vrfs D on A.vrfnew_id = D.id
JOIN backbones E on D.backbones_id = E.id