select * from (SELECT
SUBSTRING_INDEX( SUBSTRING_INDEX( a.`timeIndex`, ',', b.help_topic_id + 1 ), ',', - 1 ) AS XTime, 0 ratio
FROM
( SELECT '0,1,2,3,4,5,6,7,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23' AS timeIndex ) AS a
JOIN mysql.help_topic AS b ON b.help_topic_id < (
LENGTH( a.`timeIndex` ) - LENGTH( REPLACE ( a.`timeIndex`, ',', '' ) ) + 1
)) f
应用场景:当所查数据库数据,需要补全时可以使用,做报表类功能场景,有时间段或者区间没有数据,可以用mysql.help_topic 写死数据 ,进行代码补全