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melotusme/example.sql

Last active November 8, 2019 03:58
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sql mysql
Raw
example.sql
-- mysql 行转列， 一个字段转成多行记录
-- 使用了辅助表 mysql.help_topic
SELECT
id, b.help_topic_id, SUBSTRING_INDEX( SUBSTRING_INDEX(id,',', b.help_topic_id+1),',',-1)
FROM
( SELECT "1,2,3,4,5" AS id ) a
JOIN mysql.help_topic b ON b.help_topic_id < ( LENGTH( a.id ) - LENGTH( REPLACE ( a.id, ',', '' ))+ 1 );
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