mysql group_concat用法

http://blog.sina.com.cn/s/blog_4e808acf01009qna.html


SELECT student_id, GROUP_CONCAT(courses_id ORDER BY courses_id DESC) AS courses FROM student_courses WHERE student_id=2 GROUP BY student_id;

+------------+---------+


| student_id | courses |


+------------+---------+


|            2        | 5,4,3   |

+------------+---------+