mysql - MySQL 是否像 oracle 一样支持部分汇总？

Question

正如 oracle 文档所说，它支持部分汇总:

Partial RollupYou can also roll up so that only some of the sub-totals will be included. This partial rollup uses the following syntax:

GROUP BY expr1, ROLLUP(expr2, expr3);

In this case, the GROUP BY clause creates subtotals at (2+1=3) aggregation levels. That is, at level (expr1, expr2, expr3), (expr1, expr2), and (expr1).

http://docs.oracle.com/cd/E11882_01/server.112/e25554/aggreg.htm#DWHSG8612

MySQL 支持吗？

我试图在 MySQL 文档中搜索，但找不到任何线索。

Answer 1

关于 with rollup clause 的 Mysql 文档非常清楚:您不能向汇总子句提供列列表来指示您希望执行汇总的级别。

您可以做的是在子查询中使用 rollup 子句进行查询，在外部查询中您可以删除不需要的聚合行(或者您可以在客户端应用程序中执行此操作)。你不能在 having 子句中这样做，因为

Because the NULL values in the super-aggregate rows are placed into the result set at such a late stage in query processing, you cannot test them as NULL values within the query itself. For example, you cannot add HAVING product IS NULL to the query to eliminate from the output all but the super-aggregate rows.

On the other hand, the NULL values do appear as NULL on the client side and can be tested as such using any MySQL client programming interface.