sql 函数整理

1.locate  当不包含  locate('a',字段值)=0
update t_asset_vuln_lib set name=CONCAT('木马',name) where locate('木马',name)=0;

2.
利用mysql.help_topic表将a,b,c,d,e拆分成多行
利用having处理分组后数据
利用SUBSTRING_INDEX截取值
利用LENGTH相减和replace替换得到数组长度

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