要按月/年加入CTE的分组,可以使用日期函数将加入日期按照月份或年份进行分组。下面是一个使用CTE和日期函数的示例代码:
-- 创建一个示例表 CREATE TABLE members ( member_id INT, member_name VARCHAR(50), join_date DATE );
-- 插入示例数据 INSERT INTO members (member_id, member_name, join_date) VALUES (1, '张三', '2021-01-01'), (2, '李四', '2021-02-15'), (3, '王五', '2021-02-20'), (4, '赵六', '2021-03-10'), (5, '钱七', '2022-01-05');
-- 使用CTE按月份分组 WITH monthly_join AS ( SELECT EXTRACT(YEAR FROM join_date) AS join_year, EXTRACT(MONTH FROM join_date) AS join_month, COUNT(*) AS member_count FROM members GROUP BY join_year, join_month ) SELECT join_year, join_month, member_count FROM monthly_join ORDER BY join_year, join_month;
-- 使用CTE按年份分组 WITH yearly_join AS ( SELECT EXTRACT(YEAR FROM join_date) AS join_year, COUNT(*) AS member_count FROM members GROUP BY join_year ) SELECT join_year, member_count FROM yearly_join ORDER BY join_year;
在上述示例中,我们创建了一个名为`members`的表,并插入了一些示例数据。然后,使用CTE和日期函数`EXTRACT`将加入日期按月份和年份进行分组。在`monthly_join`和`yearly_join` CTE中,我们分别使用`EXTRACT(YEAR FROM join_date)`和`EXTRACT(MONTH FROM join_date)`来提取加入日期的年份和月份。最后,我们从CTE中选择所需的列,并按照年份和月份进行排序。