GROUP BY

完整的分析语句语法如下：

SELECT [DISTINCT] (* | expression) [AS alias] [, ...]
[GROUP BY expression [, ...] [HAVING predicates]]
[ORDER BY expression [ASC | DESC] [, ...]]
[LIMIT size OFFSET offset]

其中，GROUP BY表示按值分组。本章节内容将介绍GROUP BY语法参数说明及示例。

SELECT age GROUP BY age

SELECT account_number AS num GROUP BY num

SELECT account_number AS num, age GROUP BY num, age

SELECT LENGTH(lastname) AS len, COUNT(*) AS count GROUP BY LENGTH(lastname)