errno: 150 "外键约束格式不正确"答案

【问题标题】：errno: 150 "Foreign key constraint is incorrectly formed"errno: 150 "外键约束格式不正确"
【发布时间】：2015-06-27 17:46:29
【问题描述】：

我在尝试运行以下安装脚本时收到 150 错误。怎么了？

serverPermissions 似乎触发了错误，但我不确定为什么。据我所知，我认为外键约束都已正确映射。我可能遗漏了一些明显的东西。

-- Setup my members database
DROP DATABASE IF EXISTS mymembers;
CREATE DATABASE IF NOT EXISTS mymembers;

/*
* The list of all members in the community
*/
DROP TABLE IF EXISTS members;
CREATE TABLE members
(
id INT NOT NULL AUTO_INCREMENT,
name VARCHAR(30),
steamID3 INT NOT NULL UNIQUE,
PRIMARY KEY (id)
);

/*
* Lists all servers in operation
*/
DROP TABLE IF EXISTS servers;
CREATE TABLE servers
(
sid INT NOT NULL AUTO_INCREMENT,
sname VARCHAR(30), -- name of server (short name)
PRIMARY KEY(sid)
);

/*
* Maps a member and a server together along with a flag. 
* Record (0, 12, 1, 0) indicates member 12 has flag 0 on server 1.
*/
DROP TABLE IF EXISTS serverPermissions;
CREATE TABLE serverPermissions
(
mid INT,
sid INT,
flagid INT,
PRIMARY KEY(mid, sid, flagid),
FOREIGN KEY (mid) REFERENCES members(id),
FOREIGN KEY (sid) REFERENCES servers(sid),
FOREIGN KEY (flagid) REFERENCES flags(id)
);

/*
* flags are used to give custom permissions to players.
* For example a record may be: (0, "VIP", "This play is very important")
*/
DROP TABLE IF EXISTS flags;
CREATE TABLE flags
(
id INT NOT NULL AUTO_INCREMENT,
name VARCHAR(10),
description VARCHAR(100),
PRIMARY KEY(id)
);

【问题讨论】：

标签： mysql sql mariadb

【解决方案1】：

更改表的创建顺序。您应该在创建serverPermissions 之前创建flags 表。见Demo Here。

【讨论】：

哦，我真尴尬。我在凌晨 3 点制作数据库，所以这就是我的借口。谢谢！

【解决方案2】：

在添加外键约束时，两个表的存储类型都应为 InnoDb。将两个表的类型从 MyISAM 更改为 InnoDB

【讨论】：

【解决方案3】：

此链接 (https://mariadb.org/mariadb-innodb-foreign-key-constraint-errors/) 提供了支持外键的引擎类型的快速快照。

据我所知，以下 MariaDB 和/或 MySQL 存储引擎支持外键：

InnoDB (both innodb_plugin and XtraDB)
PBXT (https://mariadb.com/kb/en/mariadb/about-pbxt/)
SolidDB for MySQL (http://sourceforge.net/projects/soliddb/)
ScaleDB (https://mariadb.com/kb/en/mariadb/scaledb/ and http://scaledb.com/pdfs/TechnicalOverview.pdf)
MySQL Cluster NDB 7.3 or later (https://dev.mysql.com/doc/refman/5.6/en/mysql-cluster-ndb-innodb-engines.html)

【讨论】：