Mysql工作台错误1215 : cannot add foreign key to constraint

Question

所以我尝试向表添加外键，但不断收到此错误:

错误代码:1215。无法添加外键约束

代码如下

create table Students

(
    ID char(10) primary key not null,
    StudentsName varchar(30),
    Address varchar(40),
    StudentsTelephone varchar(20),
    constraint M1 check(len(NIM)=10),
    constraint M2 check(NIM like '[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]')
)

create table Lecturers

(
    CodeLecturer char(5) primary key not null,
    LecturersName varchar(30),
    Salary numeric,
    Address varchar(40),
    LecturerTelephone varchar(20),
    constraint D1 check(len(CodeLecturer)=5),
    constraint D2 check(CodeLecturer like 'D[0-9][0-9][0-9][0-9]')

)

这是外键代码

create table TrHeaderKampus

(
    TransactionCOde char(5) primary key not null,
    ID char(10) not null,
    CodeLecturer char(5) not null,
    DateandTime datetime,
    constraint H1 check(len(TransactioniCode)=5),
    constraint H2 check(TransactionCode like 'TR[0-9][0-9][0-9]'),
    foreign key(ID)REFERENCES Students ON UPDATE CASCADE ON DELETE CASCADE,
    foreign key(CodeLecturer)REFERENCES Lecturers ON UPDATE CASCADE ON DELETE CASCADE
)

Answer 1

作为 MySQL 文档 using foreign keys说明:您不仅需要提供表，还需要提供外键引用的字段。

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

将字段名称添加到它们引用的外键约束中。