mysql - 收到错误 1451 (23000) : Cannot delete or update a parent row: a foreign key constraint fails

Question

我之前使用过以下代码来获得我想要的东西，但后来我添加了一些外键，它把它弄乱了:

DELETE FROM Faculty WHERE LastName LIKE 'Z%'

DELETE FROM Courses WHERE FirstYrOffered='1999'

我只是想从表中删除一个条目，但它无法正常工作。这就是我的表格的样子:

CREATE TABLE Faculty (
FacultyID int,
FirstName varchar(30),
LastName varchar(30),
EMail varchar(60),
BirthDate DATE,
Numbr_Courses int,
PRIMARY KEY (FacultyID)
);

CREATE TABLE Courses(
CourseID int,
CourseDisc varchar(4),
CourseNum varchar(4),
NumbrCred varchar(1),
FirstYrOffered int,
CourseTitle varchar(75),
PRIMARY KEY (CourseID)
);

CREATE TABLE Faculty_Courses(
InstanceID int,
FacultyID int,
CourseDisc varchar(4),
CourseID int,
CourseNum varchar(4),
CourseTitle varchar(75),
PRIMARY KEY (InstanceID),
FOREIGN KEY (FacultyID) REFERENCES Faculty(FacultyID),
FOREIGN KEY (CourseID) REFERENCES Courses(CourseID)
);

我已经查找了 ALTER TABLE 代码示例，但并不真正理解我正在用它做什么。任何帮助将不胜感激。

Answer 1

首先，您必须从Faculty_Courses中删除相应的记录，然后从教师和类(class)表中删除记录。或者，设置 on delete cascade option在外键上。