Mysql中group by 1,2释义

下面语句：

select "name","class","score" from score_tbl where "score" > 80 group by 1,2

等价于：

select "name","class","score" from score_tbl where "score" > 80 group by "name","class"

 

含义：

　　"group by 1,2"的意思是说：按照select后面参数的第1列、第2列分组（从1开始计算，不含0）