select exam_id,substring_index(tag,',',1) '算法', substring_index(substring_index(tag,',',2),',',-1) difficulty, substring_index(tag,',',-1) duration from examination_info where tag like '%,%' #知识点substring_index(列名,分隔符,数字)数字代表索引,如果是取得是1,2两个分割出来的字符