mysql - 执行sql语法的正确语法是什么？

Question

String ag ="ALTER TABLE QUESTION"+
            "(ADD  FOREIGN KEY (a_status) REFERENCES ANSWER(a_status))";

                      stmt.executeUpdate(ag);

Error message: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'FOREIGN KEY (a_status) REFERENCES ANSWER(a_status))' at line 1

Answer 1

这应该是正确的。请参阅offical documentation :

String ag ="ALTER TABLE QUESTION ADD FOREIGN KEY (a_status) REFERENCES ANSWER(a_status)";