mysql - 无法创建外键 MySQL Workbench

Question

出于某种原因，我需要在两个表之间创建外键方面的帮助，但我反复被告知客户编号不存在

这是第一个表的代码

SET FOREIGN_KEY_CHECKS = 0;
DROP TABLE IF EXISTS Customer;
CREATE TABLE Customer
(
    CustomerNumber int NOT NULL,
    CustomerName varchar(255),
    CustomerAddress varchar(255),
    CustomerPhoneNumber varchar(255),
    JoinDate varchar(255),
    PetName varchar(255),
    PayScheme varchar(255),
    PremiumPayDate varchar(255),
    PRIMARY KEY (CustomerNumber)
    );

这是第二个的代码

DROP TABLE IF EXISTS Policies;    
CREATE TABLE Policies
(
    PolicyID int NOT NULL,
    PolicyNumber int NOT NULL,
    PetType varchar(255),
    EffectiveDate varchar(255),
    PRIMARY KEY (PolicyID),
        CONSTRAINT fk_CustomerNumber
FOREIGN KEY (CustomerNumber) 
REFERENCES Customer(CustomerNumber)
);

我反复被告知关键列“客户编号”不存在

Answer 1

Policies 表缺少 customerNumber 列。您需要在对其声明外键约束之前添加它。试试这个:

DROP TABLE IF EXISTS Policies;    
CREATE TABLE Policies
(
    PolicyID int NOT NULL,
    PolicyNumber int NOT NULL,
    PetType varchar(255),
    CustomerNumber int NOT NULL,  --Added here
    EffectiveDate varchar(255),
    PRIMARY KEY (PolicyID),
        CONSTRAINT fk_CustomerNumber
FOREIGN KEY (CustomerNumber) 
REFERENCES Customer(CustomerNumber)
);