group by rollup和 group by cube区别

1、分组依据为一列时 一、使用group by分组查询 select exam_no,avg (result) as 平均分 from result_info group by exam_no 查询结果以下:  二、使用group by rollup 和group by cube的结果 select exam_no,avg(result) as 平均分 from result_info gro
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