无法添加外键约束 - MySQL ERROR 1215 (HY000)

Cannot add foreign key constraint - MySQL ERROR 1215 (HY000)(无法添加外键约束 - MySQL ERROR 1215 (HY000))

问题描述

我正在尝试为健身房管理系统创建数据库，但我不知道为什么会出现此错误.我试图在这里搜索答案，但找不到.

I am trying to create database for gym management system, but I can't figure out why I am getting this error. I've tried to search for the answer here, but I couldn't find it.

ERROR 1215 (HY000): Cannot add foreign key constraint

CREATE TABLE sales(
    saleId int(100) NOT NULL AUTO_INCREMENT,
    accountNo int(100) NOT NULL,
    payName VARCHAR(100) NOT NULL,
    nextPayment DATE,
    supplementName VARCHAR(250),
    qty int(11),
    workoutName VARCHAR(100),
    sDate datetime NOT NULL DEFAULT NOW(),
    totalAmount DECIMAL(11,2) NOT NULL,
    CONSTRAINT PRIMARY KEY(saleId, accountNo, payName),
    CONSTRAINT FOREIGN KEY(accountNo) REFERENCES accounts(accountNo) ON DELETE CASCADE ON UPDATE CASCADE,
    CONSTRAINT FOREIGN KEY(payName) REFERENCES paymentFor(payName) ON DELETE CASCADE ON UPDATE CASCADE,
    CONSTRAINT FOREIGN KEY(supplementName) REFERENCES supplements(supplementName) ON DELETE CASCADE ON UPDATE CASCADE,
    CONSTRAINT FOREIGN KEY(workoutName) REFERENCES workouts(workoutName) ON DELETE CASCADE ON UPDATE CASCADE
);
    ALTER TABLE sales AUTO_INCREMENT = 2001;

这是父表.

CREATE TABLE accounts(
    accountNo int(100) NOT NULL AUTO_INCREMENT,
    accountType VARCHAR(100) NOT NULL,
    firstName VARCHAR(50) NOT NULL,
    lastName VARCHAR(60) NOT NULL,
    birthdate DATE NOT NULL,
    gender VARCHAR(7),
    city VARCHAR(50) NOT NULL,
    street VARCHAR(50),
    cellPhone VARCHAR(10),
    emergencyPhone VARCHAR(10),
    email VARCHAR(150) NOT NULL,
    description VARCHAR(350),
    occupation VARCHAR(50),
    createdOn datetime NOT NULL DEFAULT NOW(),
    CONSTRAINT PRIMARY KEY(accountNo)
);
    ALTER TABLE accounts AUTO_INCREMENT = 1001; 


CREATE TABLE supplements(
    supplementId int(100) NOT NULL AUTO_INCREMENT,
    supplementName VARCHAR(250) NOT NULL,
    manufacture VARCHAR(100),
    description VARCHAR(150),
    qtyOnHand INT(5),
    unitPrice DECIMAL(11,2),
    manufactureDate DATE,
    expirationDate DATE,
    CONSTRAINT PRIMARY KEY(supplementId, supplementName)
);
    ALTER TABLE supplements AUTO_INCREMENT = 3001;

CREATE TABLE workouts(
    workoutId int(100) NOT NULL AUTO_INCREMENT,
    workoutName VARCHAR(100) NOT NULL,
    description VARCHAR(7500) NOT NULL,
    duration VARCHAR(30),
    CONSTRAINT PRIMARY KEY(workoutId, workoutName)
);
    ALTER TABLE workouts AUTO_INCREMENT = 4001;



CREATE TABLE paymentFor(
    payId int(100) NOT NULL AUTO_INCREMENT,
    payName VARCHAR(100) NOT NULL,
    amount DECIMAL(11,2),
    CONSTRAINT PRIMARY KEY(payId, payName)
);
    ALTER TABLE paymentFor AUTO_INCREMENT = 5001;

你们能帮我解决这个问题吗?谢谢.

Can you guys help me with this problem? Thanks.

推荐答案

对于要定义为外键的字段，所引用的父字段必须具有在其上定义的索引.

For a field to be defined as a foreign key, the referenced parent field must have an index defined on it.

根据关于 foreign key 约束的文档:

As per documentation on foreign key constraints:

REFERENCES parent_tbl_name (index_col_name,...)

REFERENCES parent_tbl_name (index_col_name,...)

分别在 workouts.workoutName、paymentFor.paymentName 和 supplements.supplements.supplementName 上定义一个 INDEX.并确保子列定义必须与其父列定义匹配.

Define an INDEX on workouts.workoutName, paymentFor.paymentName, and supplements.supplementName respectively. And make sure that child column definitions must match with those of their parent column definitions.

修改workouts表定义如下:

CREATE TABLE workouts(
    workoutId int(100) NOT NULL AUTO_INCREMENT,
    workoutName VARCHAR(100) NOT NULL,
    description VARCHAR(7500) NOT NULL,
    duration VARCHAR(30),

    KEY ( workoutName ), -- <---- this is newly added index key

    CONSTRAINT PRIMARY KEY(workoutId, workoutName)
);

修改supplements表定义如下:

CREATE TABLE supplements(
    supplementId int(100) NOT NULL AUTO_INCREMENT,
    supplementName VARCHAR(250) NOT NULL,
    manufacture VARCHAR(100),
    description VARCHAR(150),
    qtyOnHand INT(5),
    unitPrice DECIMAL(11,2),
    manufactureDate DATE,
    expirationDate DATE,

    KEY ( supplementName ), -- <---- this is newly added index key

    CONSTRAINT PRIMARY KEY(supplementId, supplementName)
);

修改paymentFor表定义如下:

CREATE TABLE paymentFor(
    payId int(100) NOT NULL AUTO_INCREMENT,
    payName VARCHAR(100) NOT NULL,
    amount DECIMAL(11,2),

    KEY ( payName ), -- <---- this is newly added index key

    CONSTRAINT PRIMARY KEY(payId, payName)
);

现在，改变子表定义如下:

Now, change child table definition as below:

CREATE TABLE sales(
    saleId int(100) NOT NULL AUTO_INCREMENT,
    accountNo int(100) NOT NULL,
    payName VARCHAR(100) NOT NULL,
    nextPayment DATE,
    supplementName VARCHAR(250) NOT NULL,
    qty int(11),
    workoutName VARCHAR(100) NOT NULL,
    sDate datetime NOT NULL DEFAULT NOW(),
    totalAmount DECIMAL(11,2) NOT NULL,
    CONSTRAINT PRIMARY KEY(saleId, accountNo, payName),
    CONSTRAINT FOREIGN KEY(accountNo) 
       REFERENCES accounts(accountNo) 
       ON DELETE CASCADE ON UPDATE CASCADE,
    CONSTRAINT FOREIGN KEY(payName) 
       REFERENCES paymentFor(payName) 
       ON DELETE CASCADE ON UPDATE CASCADE,
    CONSTRAINT FOREIGN KEY(supplementName) 
       REFERENCES supplements(supplementName) 
       ON DELETE CASCADE ON UPDATE CASCADE,
    CONSTRAINT FOREIGN KEY(workoutName) 
       REFERENCES workouts(workoutName) 
       ON DELETE CASCADE ON UPDATE CASCADE
);

参考:

• MySQL 使用外键约束

[CONSTRAINT [符号]] 外键
[index_name] (index_col_name, ...)
参考 tbl_name (index_col_name,...)
[ON DELETE reference_option]
[ON UPDATE reference_option]

[CONSTRAINT [symbol]] FOREIGN KEY
[index_name] (index_col_name, ...)
REFERENCES tbl_name (index_col_name,...)
[ON DELETE reference_option]
[ON UPDATE reference_option]

reference_option:
限制 |级联 |设置空 |没有行动

reference_option:
RESTRICT | CASCADE | SET NULL | NO ACTION

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