mysql 行转列

1： 一个字段 拆成多行 video_id（1;2;3;4）

CREATE TABLE temp_0825 AS 
SELECT * FROM  (
SELECT a.`moblie`,a.`create_time`,a.`ret_msg`,SUBSTRING_INDEX(SUBSTRING_INDEX(a.`video_id`,';',b.help_topic_id+1),';',-1) AS num
FROM 
a5_pps_activity_partake_his a
JOIN
mysql.help_topic b
ON b.help_topic_id < (LENGTH(a.video_id) - LENGTH(REPLACE(a.video_id,';',''))+1)
WHERE  a.`activity_id` ='112017081501'
ORDER BY a.moblie  
) tt ;

2: 多行转一行 

SELECT moblie,GROUP_CONCAT(num ORDER BY num ASC) 
FROM temp_0825 
GROUP BY moblie;