题解 | #修复串列了的记录#
修复串列了的记录
http://www.nowcoder.com/practice/a5475ed3b5ab4de58e2ea426b4b2db76
select exam_id ,
substring_index(tag ,',',1) as tag ,
substring_index(substring_index(tag ,',',-2),',',1) as difficulty ,
substring_index(tag ,',',-1) as duration
from examination_info
where char_length(tag)>3
substring_index(tag ,',',1) as tag ,
substring_index(substring_index(tag ,',',-2),',',1) as difficulty ,
substring_index(tag ,',',-1) as duration
from examination_info
where char_length(tag)>3
