SQL Lesson 10: 在查询中进行统计I (Pt. 1)

对全部结果数据做统计

SELECT AGG_FUNC(column_or_expression) AS aggregate_description, …
FROM mytable
WHERE constraint_expression;

常见统计函数

用分组的方式统计

SELECT AGG_FUNC(column_or_expression) AS aggregate_description, …
FROM mytable
WHERE constraint_expression
GROUP BY column;

使用