Question

车辆

+--------------------+--------------+------+-----+---------+
| Field              | Type         | Null | Key | Default | 
+--------------------+--------------+------+-----+---------+
| id                 | int(11)      | NO   | Pk  | NULL    |       
| model              | varchar(35)  | NO   |     | NULL    |            
+--------------------+--------------+------+-----+---------+

信息

+--------------------+--------------+------+-----+---------+
| Field              | Type         | Null | Key | Default | 
+--------------------+--------------+------+-----+---------+
| id                 | int(11)      | NO   | Pk  | NULL    |       
| vehicle_id         | varchar(35)  | NO   | FK  | NULL    |       
| location           | varchar(35)  | NO   |     | NULL    |       
+--------------------+--------------+------+-----+---------+

Axle 1

+--------------------+--------------+------+-----+---------+
| Field              | Type         | Null | Key | Default | 
+--------------------+--------------+------+-----+---------+
| id                 | int(11)      | NO   | Pk  | NULL    |       
| vehicle_id         | varchar(35)  | NO   | FK  | NULL    |       
| weight             | varchar(35)  | NO   |     | NULL    |       
+--------------------+--------------+------+-----+---------+

Axle 2

+--------------------+--------------+------+-----+---------+
| Field              | Type         | Null | Key | Default | 
+--------------------+--------------+------+-----+---------+
| id                 | int(11)      | NO   | Pk  | NULL    |       
| vehicle_id         | varchar(35)  | NO   | FK  | NULL    |       
| weight             | varchar(35)  | NO   |     | NULL    |       
+--------------------+--------------+------+-----+---------+

我希望创建一个查询，它将返回所有表中具有公共vehicle_id的所有字段。 vehicle_id是3个表（info，axle1，axis 2）中每个表中对Vehicle表中主键的引用。有人可以解释一下我可能会这样做吗？我尝试使用多个连接，但它没有用！非常感谢。

编辑：

我试过的查询是;

SELECT * 
      FROM  Vehicle
      JOIN info, axle1, axle 2
      ON vehicle.id = axle1.vehicle_id 
     AND vehicle.id = axle2.vehicle_id AND vehicle.id = info.vehicle_id

Answer 1

请改为尝试：

SELECT *
FROM Vehicle v
INNER JOIN Info   i ON          v.id = i.vehicle_id
INNER JOIN Axle1 a1 ON i.vehicle_id  = a1.vehicle_id
INNER JOIN Axle2 a2 ON a1.vehicle_id = a2.vehicle_id

Answer 2

检查此链接：mySQL get information from multiple tables in one query我认为有一个可能适用的示例

您只需要为每个表指定一个标识符，这样您就可以指定在引用字段时您在谈论哪个表。然后，确保将所有ID链接为条件，这样就可以省去标识符不匹配的所有组合。那将是：

SELECT * FROM Vehicle v, Info i, Axle1 a1, Axle2 a2 WHERE v.id == a1.vehicle_id AND v.id == a2.vehicle_id AND v.id == i.vehicle_id

如何使用mySQL查询链接4个表

2 个答案: