题解 | #修复串列了的记录#

SELECT
exam_id,
	SUBSTRING_INDEX(SUBSTRING_INDEX(tag,',',1),',',-1) as tag,
	SUBSTRING_INDEX(SUBSTRING_INDEX(tag,',',2),',',-1) as difficulty,
	SUBSTRING_INDEX(tag,',',-1) as duration
from examination_info
#查找录错了的记录
where tag LIKE '%,%';