ROLLUP 功能简述ROLLUP 可以在普通的 GROUP BY 聚合的情况下,增加更多层次的聚集输出。比如以下这条 SQL:SELECTyear,country,product,SUM(profit)ASprofitFROMsalesGROUPBYyear,country,productWITHROLLUP;除了计算按照年份、国家、产品分组的利润总和,也会计算按照年份、国家(GROUP BY year, country),按照年份(GROUP BY year)和所有(No GROUP BY)的利润总和。结果如下:+------+---------+------------+--------+|year|country|product|profit|rolluplevel+------+---------+------------+--------+|2000|Finland|Computer|1500|3<-- GROUP BY year, country, product|2000|Finland|Phone|100|3|2000|Finland|NULL|1600|2<-- GROUP BY year, country|2000|India|Calculator|150|3|2000|India|Computer|1200|3|2000|India|NULL|1350|2<
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