Mysql中group by 1,2釋義

下面語句：

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

等價於：

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

 

含義：

　　"group by 1,2"的意思是說：按照select后面參數的第1列、第2列分組（從1開始計算，不含0）