MySQL"ERROR 1005(HY000):无法创建表'foo.#sql-12c_4'(错误号:150)"

Question

我正在努力在数据库中创建一些表foo,但每次我最终都得到关于外键的errno 150.首先,这是我创建表的代码:

CREATE TABLE Clients
(
client_id                CHAR(10)  NOT NULL ,
client_name              CHAR(50)  NOT NULL ,
provisional_license_num  CHAR(50)  NOT NULL ,
client_address           CHAR(50)  NULL ,
client_city              CHAR(50)  NULL ,
client_county            CHAR(50)  NULL ,
client_zip               CHAR(10)  NULL ,
client_phone             INT       NULL ,
client_email             CHAR(255) NULL ,
client_dob               DATETIME  NULL ,
test_attempts            INT       NULL
);
CREATE TABLE Applications
(
application_id   CHAR(10) NOT NULL ,
office_id        INT      NOT NULL ,
client_id        CHAR(10) NOT NULL ,
instructor_id    CHAR(10) NOT NULL ,
car_id           CHAR(10) NOT NULL ,
application_date DATETIME NULL 
);
CREATE TABLE Instructors
(
instructor_id      CHAR(10)  NOT NULL ,
office_id          INT       NOT NULL ,
instructor_name    CHAR(50)  NOT NULL ,
instructor_address CHAR(50)  NULL ,
instructor_city    CHAR(50)  NULL ,
instructor_county  CHAR(50)  NULL ,
instructor_zip     CHAR(10)  NULL ,
instructor_phone   INT       NULL ,
instructor_email   CHAR(255) NULL ,
instructor_dob     DATETIME  NULL ,
lessons_given      INT       NULL 
);
CREATE TABLE Cars
(
car_id             CHAR(10) NOT NULL ,
office_id          INT      NOT NULL ,
engine_serial_num  CHAR(10) NULL ,
registration_num   CHAR(10) NULL ,
car_make           CHAR(50) NULL ,
car_model          CHAR(50) NULL 
);
CREATE TABLE Offices
(
office_id       INT       NOT NULL ,
office_address  CHAR(50)  NULL ,
office_city     CHAR(50)  NULL ,
office_County   CHAR(50)  NULL ,
office_zip      CHAR(10)  NULL ,
office_phone    INT       NULL ,
office_email    CHAR(255) NULL 
);
CREATE TABLE Lessons
(
lesson_num     INT            NOT NULL ,
client_id      CHAR(10)       NOT NULL ,
date           DATETIME       NOT NULL ,
time           DATETIME       NOT NULL ,
milegage_used  DECIMAL(5, 2)  NULL ,
progress       CHAR(50)       NULL 
);
CREATE TABLE DrivingTests
(
test_num     INT       NOT NULL ,
client_id    CHAR(10)  NOT NULL ,
test_date    DATETIME  NOT NULL ,
seat_num     INT       NOT NULL ,
score        INT       NULL ,
test_notes   CHAR(255) NULL 
);

ALTER TABLE Clients ADD PRIMARY KEY (client_id);
ALTER TABLE Applications ADD PRIMARY KEY (application_id);
ALTER TABLE Instructors ADD PRIMARY KEY (instructor_id);
ALTER TABLE Offices ADD PRIMARY KEY (office_id);
ALTER TABLE Lessons ADD PRIMARY KEY (lesson_num);
ALTER TABLE DrivingTests ADD PRIMARY KEY (test_num);
ALTER TABLE Applications ADD CONSTRAINT FK_Applications_Offices FOREIGN KEY (office_id) REFERENCES Offices (office_id);
ALTER TABLE Applications ADD CONSTRAINT FK_Applications_Clients FOREIGN KEY (client_id) REFERENCES Clients (client_id);
ALTER TABLE Applications ADD CONSTRAINT FK_Applications_Instructors FOREIGN KEY (instructor_id) REFERENCES Instructors (instructor_id);
ALTER TABLE Applications ADD CONSTRAINT FK_Applications_Cars FOREIGN KEY (car_id) REFERENCES Cars (car_id);
ALTER TABLE Lessons ADD CONSTRAINT FK_Lessons_Clients FOREIGN KEY (client_id) REFERENCES Clients (client_id);
ALTER TABLE Cars ADD CONSTRAINT FK_Cars_Offices FOREIGN KEY (office_id) REFERENCES Offices (office_id);
ALTER TABLE Clients ADD CONSTRAINT FK_DrivingTests_Clients FOREIGN KEY (client_id) REFERENCES Clients (client_id);

这些是我得到的错误:

mysql> ALTER TABLE Applications ADD CONSTRAINT FK_Applications_Cars FOREIGN KEY
(car_id) REFERENCES Cars (car_id);
ERROR 1005 (HY000): Can't create table 'foo.#sql-12c_4' (errno: 150)

我跑了SHOW ENGINE INNODB STATUS,它提供了更详细的错误描述:

------------------------
LATEST FOREIGN KEY ERROR
------------------------
100509 20:59:49 Error in foreign key constraint of table foo/#sql-12c_4:
 FOREIGN KEY (car_id) REFERENCES Cars (car_id):
Cannot find an index in the referenced table where the
referenced columns appear as the first columns, or column types
in the table and the referenced table do not match for constraint.
Note that the internal storage type of ENUM and SET changed in
tables created with >= InnoDB-4.1.12, and such columns in old tables
cannot be referenced by such columns in new tables.
See http://dev.mysql.com/doc/refman/5.1/en/innodb-foreign-key-constraints.html
for correct foreign key definition.
------------

我在StackOverflow和其他地方搜索过 - 在这里发现了一篇有用的博客文章,其中有关于如何解决此错误的指示 - 但我无法弄清楚出了什么问题.任何帮助,将不胜感激!

Answer 1

你应该把car_id作为汽车的主键.

Answer 2

注意:我遇到了同样的问题,这是因为引用的字段在2个不同的表中使用了不同的排序规则(它们具有完全相同的类型).

确保所有引用的字段具有相同的类型和相同的排序规则!

Answer 3

检查BOTH表是否具有相同的ENGINE.例如,如果你有:

CREATE Table FOO ();

和:

CREATE Table BAR () ENGINE=INNODB;

如果您尝试从表BAR到表FOO创建约束,它将无法在某些MySQL版本上运行.

通过以下方式修复此问题:

CREATE Table FOO () ENGINE=INNODB;

Answer 4

微妙,但这个错误让我失望,因为我忘了将smallint列声明为unsigned以匹配引用的现有表,即"smallint unsigned".有一个无符号和一个未签名导致MySQL阻止在新表上创建外键.

id smallint(3) not null

为了外键,不匹配,

id smallint(3) unsigned not null

Answer 5

当我尝试以下时,我得到了这个毫无价值且无法提供信息的错误:

ALTER TABLE `comments` ADD CONSTRAINT FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE SET NULL ON UPDATE CASCADE;

我的问题出在我的评论表中,user_id被定义为:

`user_id` int(10) unsigned NOT NULL

所以...在我的情况下,问题是NOT NULL和ON DELETE SET NULL之间的冲突.

Answer 6

两个表都需要具有相同的字符集.

例如

CREATE TABLE1 (
  FIELD1 VARCHAR(100) NOT NULL PRIMARY KEY,
  FIELD2 VARCHAR(100) NOT NULL
)ENGINE=INNODB CHARACTER SET utf8 COLLATE utf8_bin;

至

CREATE TABLE2 (
  Field3 varchar(64) NOT NULL PRIMARY KEY,
  Field4 varchar(64) NOT NULL,
  CONSTRAINT FORIGEN KEY (Field3) REFERENCES TABLE1(FIELD1)
) ENGINE=InnoDB;

会失败,因为他们有不同的字符集.这是另一个微妙的失败,其中mysql返回相同的错误.