MySQL 逗号分隔数据进行拆分去重

SELECt
	substring_index( substring_index( a."字段名", ',', b.help_topic_id + 1 ), ',',- 1 ) AS result 
FROM
	"表名" a
	JOIN mysql.help_topic b ON b.help_topic_id < ( length( a."字段名" ) - length( REPLACe ( "字段名", ',', '' ) ) + 1 ) 
GROUP BY
	result

SELECT
	substring_index( substring_index( a."字段名1", ',', b.help_topic_id + 1 ), ',',- 1 ) AS result 
FROM
	"表名1" a
	JOIN mysql.help_topic b ON b.help_topic_id < ( length( a."字段名1" ) - length( REPLACE ( "字段名1", ',', '' ) ) + 1 )
	JOIN "表名2" c
	JOIN mysql.help_topic d ON d.help_topic_id < ( length( c."字段名2" ) - length( REPLACE ( c."字段名2", ',', '' ) ) + 1 )
	JOIN "表名3" m ON a."字段名2" = m."字段名3" 
WHERe
	"条件" 
GROUP BY
	result

请替换代码中的 "表名" 、"字段名" 、"条件"

*注意：执行SQL需要开启 mysql.help_topic 表的 读权限