mysql 语句将字符串转行

示例

(
SELECT 考籍号,GROUP_CONCAT(kemu) ‘kemu2’ from (
SELECT 考籍号,substring_index(substring_index(t.考试科目,’,’, b.help_topic_id + 1), ‘,’, -1) ‘kemu’
FROM 省考籍信息77923 t
join mysql.help_topic b ON b.help_topic_id < (LENGTH(t.考试科目) - LENGTH(REPLACE(t.考试科目, ‘,’, ‘’)) + 1)
) t where t.kemu<>’’ GROUP BY 考籍号
)

########################
**

查询两张表 考试科目不一样的人 使用身份证号做关联

**
select * from b1 a
where not exists (select 1 from b2 b where a.kemu=b.kemu and a.身份证号=b.身份证号);

select * from b2 a
where not exists (select 1 from b1 b where a.kemu=b.kemu and a.身份证号=b.身份证号);