1.创建一个日期表
我们需要创建一个包含所有日期的表。该表应该至少包含日期和星期几两个字段。可以使用以下命令创建一个日期表:
dar` (
`date` date NOT NULL,t(11) NOT NULL,
PRIMARY KEY (`date`)
2.插入日期数据
插入日期数据可以使用以下命令:
dar` (`date`,`day_of_week`)
SELECT DATE_ADD('2000-01-01',INTERVAL a.i*10000 + b.i*1000 + c.i*100 + d.i*10 + e.i DAY),
DAYOFWEEK(DATE_ADD('2000-01-01',INTERVAL a.i*10000 + b.i*1000 + c.i*100 + d.i*10 + e.i DAY))
FROM (SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) a
CROSS JOIN (SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) b
CROSS JOIN (SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) c
CROSS JOIN (SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) d
CROSS JOIN (SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) e
WHERE DATE_ADD('2000-01-01',INTERVAL a.i*10000 + b.i*1000 + c.i*100 + d.i*10 + e.i DAY) BETWEEN '2000-01-01' AND '2020-12-31';
有了日期表后,我们可以使用分组函数来生成日历。以下是一些示例:
-- 查找2021年1月的日历
SELECT `date`,`day_of_week`dar`
WHERE `date` BETWEEN '2021-01-01' AND '2021-01-31';
-- 计算2021年1月每一天的订单总数t`
FROM `orders`
WHERE `date` BETWEEN '2021-01-01' AND '2021-01-31'
GROUP BY `date`;
-- 计算2021年1月每一天的订单总数和销售总额tount`) AS `total_sales`
FROM `orders`
WHERE `date` BETWEEN '2021-01-01' AND '2021-01-31'
GROUP BY `date`;
通过以上步骤,我们可以使用分组函数来生成日历,以及进行相关的统计计算。
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