Question

我打算创建一个包含两列（bus_id，bus_passengers）的表。 bus_id将成为主键，并且将是来自另一个创建的表的外键，该表称为“beacap_locationLog”，列为node_id。

这是我写的代码（mySQL）：

CREATE TABLE Bus(
   bus_id INT (10) UNSIGNED NOT NULL,
   bus_passengers INT,
   PRIMARY KEY (bus_id),
   FOREIGN KEY (bus_id) REFERENCES beacap_locationLog(node_id)
);

它给了我这个错误：

#1005 - Can't create table 'pei.Bus' (errno: 150)

我不知道问题是什么。

Answer 1

不能拥有主+外键！具有相同名称的列

Shoul会是这样的！
- 我已经添加了一个新专栏!!

 CREATE TABLE Bus(
       bus_id INT (10) UNSIGNED NOT NULL,
       bus_passengers INT,
       node_id_fk int,
       PRIMARY KEY (bus_id),
       FOREIGN KEY (node_id_fk) REFERENCES beacap_locationLog(node_id)
    );

node_id_fk和node_id也必须具有相同的类型！

好的，请参阅完整示例：

mysql> create table beacap_locationLog(
     -> node_id int
    -> );

Query OK, 0 rows affected (0.26 sec)

mysql> CREATE TABLE Bus(
    ->        bus_id INT (10) UNSIGNED NOT NULL,
    ->        bus_passengers INT,
    ->        node_id_fk int,
    ->        PRIMARY KEY (bus_id),
    ->        FOREIGN KEY (node_id_fk) REFERENCES beacap_locationLog(node_id)
    ->     );
Query OK, 0 rows affected (0.03 sec)

mysql> desc beacap_locationLog;
+---------+---------+------+-----+---------+-------+
| Field   | Type    | Null | Key | Default | Extra |
+---------+---------+------+-----+---------+-------+
| node_id | int(11) | YES  |     | NULL    |       |
+---------+---------+------+-----+---------+-------+
1 row in set (0.00 sec)

mysql> desc Bus;
+----------------+------------------+------+-----+---------+-------+
| Field          | Type             | Null | Key | Default | Extra |
+----------------+------------------+------+-----+---------+-------+
| bus_id         | int(10) unsigned | NO   | PRI | NULL    |       |
| bus_passengers | int(11)          | YES  |     | NULL    |       |
| node_id_fk     | int(11)          | YES  | MUL | NULL    |       |
+----------------+------------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

mysql>

TBL总线定义

mysql> show create table Bus\G
           Table: Bus
    Create Table: CREATE TABLE Bus (
      bus_id int(10) unsigned NOT NULL,
      bus_passengers int(11) default NULL,
      node_id_fk int(11) default NULL,
      PRIMARY KEY  (bus_id),
      KEY node_id_fk (node_id_fk)
    ) ENGINE=MyISAM DEFAULT CHARSET=latin1
    1 row in set (0.01 sec)

外键中的错误号150

1 个答案: