消息是什么意思，我如何修复我的代码？

Question

  

您的SQL语法有错误;检查手册   与您的MySQL服务器版本对应，以便使用正确的语法   在''students'（'subject_id'）附近，在DELETE CASCADE上更新CASCADE   外键（第8行的主题'

CREATE TABLE Entries
 (
entry_id int NOT NULL,
subject_id int NOT NULL,
student_id int NOT NULL,
exam_date int,
PRIMARY KEY (subject_id),
FOREIGN KEY (student_id) REFERENCES 'students'('student_id')
ON UPDATE CASCADE ON DELETE CASCADE 
FOREIGN KEY (subject_id) REFERENCES 'subjects'('subject_id')
ON UPDATE CASCADE ON DELETE CASCADE 
)

Answer 1

您必须删除单引号arround列和表名：

CREATE TABLE Entries
 (
entry_id int NOT NULL,
subject_id int NOT NULL,
student_id int NOT NULL,
exam_date int,
PRIMARY KEY (subject_id),
FOREIGN KEY (student_id) REFERENCES students(student_id)
ON UPDATE CASCADE ON DELETE CASCADE 
)

并且没有必要两次添加密钥