mysql errno 150

Question

我有两个表'member'和'book'定义为：

create table member(

      mem_id bigint(11) unsigned auto_increment not null primary key,
      firstname varchar(20) not null,
      lastname varchar(20) not null,
      gender varchar(1) not null
);

create table book(

      book_id varchar(15) not null primary key,
      isbn varchar(15) not null,
      book_name varchar(100) not null
);

现在我想创建一个名为'return_book'的follwing表：

create table return_book(

      mem_id bigint(11) unsigned not null,
      book_id varchar(15) , 
      date date,    
      primary key(mem_id, book_id),
      foreign key(mem_id) references member(mem_id) 
      ON DELETE CASCADE,
      foreign key(book_id) references book(book_id)
      ON DELETE NO ACTION
      ON UPDATE CASCADE            
);

但是我总是得到以下错误：“无法创建表return_book” 请帮忙。

Answer 1

您有语法错误

create table return_book(
mem_id bigint(11) unsigned not null,
book_id varchar(15) , 
date date,  
  primary key(mem_id, book_id),
  foreign key(mem_id) references member(mem_id) 
  ON DELETE CASCADE,
  foreign key(book_id) references book(book_id)
  ON DELETE NO ACTION
  ON UPDATE CASCADE            
);

Answer 2

'member'表中的列名'mem_id'中有一个拼写错误：D！此外，我还了解到引用的列和引用列必须具有相同的类型。