获取错误 1451 (23000)：无法删除或更新父行：外键约束失败

Question

我之前用过下面的代码来得到我想要的东西，但后来我添加了一些外键，它把它搞砸了：

DELETE FROM Faculty WHERE LastName LIKE 'Z%'

DELETE FROM Courses WHERE FirstYrOffered='1999'

只是我想从 table 中删除一个条目，但它无法正常工作。这是我的 table 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)
);

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

Answer 1

首先你必须从Faculty_Courses中删除相应的记录，然后从faculty和courses表中删除记录。或者，在外键上设置 on delete cascade option。

获取错误 1451 (23000)：无法删除或更新父行：外键约束失败

Getting a ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constraint fails

mysql

sql-delete

alter