错误代码：1822。无法添加外键约束。引用表"student1"中缺少约束"hod_ibfk_1"的索引 0.000 秒？

Question

create table Hod(
BranchId int(5),
Branch varchar(10),
Hod_Name varchar(10),
Hod_number int(15),
foreign key (BranchId) references student1(BranchId)
);

Answer 1

引用字段上添加一个索引之前创建外键:

alter table student1 add index(BranchId);
create table Hod(
BranchId int(5),
Branch varchar(10),
Hod_Name varchar(10),
Hod_number int(15),
foreign key (BranchId) references student1(BranchId)
);