Creating SQL with multiple grouping sets.
创建具有多个分组集的sql。
This ROLLUP ends up being equivalent to the following grouping sets.
最终的这个ROLLUP相当于以下分组集。
Multiple slices of data can be returned in a single query by using grouping sets or super-groups (such as ROLLUP) in the GROUP-BY clause of the SQL statement.
通过在sql语句的GROUP BY子句中使用多个分组集或超级组(比如rollup)，可以在一个查询中返回数据的多个切片。
While the ordering of the grouping columns does not matter for a single grouping set or multiple grouping sets, the order of the columns does matter for ROLLUP.
对于单一分组集或多个分组集，分组列的次序是无所谓的；但是对于ROLLUP，列的次序不能随意安排。
Enumerations provide an alternative method of not only defining but also grouping sets of integral constants.
枚举提供了一种替代的方法，不但定义了整数常量集，而且还把它们聚集成组。
Enumerations provide an alternative method of not only defining but also grouping sets of integral constants.
枚举提供了一种替代的方法，不但定义了整数常量集，而且还把它们聚集成组。
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