group by rollup和 group by cube區別

1、分組依據爲一列時 一、使用group by分組查詢 select exam_no,avg (result) as 平均分 from result_info group by exam_no 查詢結果以下:  二、使用group by rollup 和group by cube的結果 select exam_no,avg(result) as 平均分 from result_info gro
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