17.mysql原生按逗号拆分函数实现

SELECT DISTINCT id,

substring_index( substring_index( a.replacedPartCodes, ',', b.help_topic_id + 1 ), ',',- 1 )

FROM

supersession a

JOIN mysql.help_topic b ON b.help_topic_id < ( length( a.replacedPartCodes ) - length( REPLACE ( a.replacedPartCodes, ',', '' ) ) + 1 ) LIMIT 100