Mysql 简明教程
MySQL - Aggregate Functions
一般来说，聚合是将作为单个实体结合在一起的一组对象的考虑因素。MySQL 提供了一组聚合函数，这些函数对表列的所有实体执行操作，并将它们视为单个单元。以下是 MySQL 聚合函数 −
In general, aggregation is a consideration of a collection of objects that are bound together as a single entity. MySQL provides a set of aggregate functions that perform operations on all the entities of the column of a table considering them as a single unit. Following are the MySQL aggregate functions −