mysql滑动订单问题原理与解决方法实例分析

本文实例讲述了mysql滑动订单问题原理与解决方法。分享给大家供大家参考，具体如下：

先根据以下代码来创建表MonthlyOrders并导入一定的数据

CREATE TABLE MonthlyOrders(ordermonth DATE,ordernum INT UNSIGNED,PRIMARY KEY (ordermonth));

执行下面的SQL查询实现每个月返回上一年度的滑动订单总数

SELECT  DATE_FORMAT(a.ordermonth, '%Y%m') AS frommonth,  DATE_FORMAT(b.ordermonth, '%Y%m') AS tomonth,  SUM(c.ordernum) AS ordersFROM monthlyorders aINNER JOIN monthlyorders b  ON DATE_ADD(a.ordermonth, INTERVAL 11 MONTH) = b.ordermonthINNER JOIN monthlyorders c  ON c.ordermonth BETWEEN a.ordermonth AND b.ordermonthGROUP BY a.ordermonth,b.ordermonth;

该查询首先对MonthlyOrders表进行自连接。a表用做下边界(frommonth)，b表用做上边界(tomonth)。连接的条件为:

DATE_ADD(a.ordermonth, INTERVAL 11 MONTH) = b.ordermonth

完成自连接之后，需要对订单进行统计。这时需要再进行一次自连接，得到范围内每个月的订单数量。因此连接的条件为

c.ordermonth BETWEEN a.ordermonth AND b.ordermonth

SELECT  DATE_FORMAT(a.ordermonth, '%Y%m') AS frommonth,  DATE_FORMAT(b.ordermonth, '%Y%m') AS tomonth,  SUM(c.ordernum) AS ordersFROM monthlyorders aINNER JOIN monthlyorders b  ON DATE_ADD(a.ordermonth, INTERVAL 2 MONTH) = b.ordermonth  AND MONTH(a.ordermonth) % 3 = 1INNER JOIN monthlyorders c  ON c.ordermonth BETWEEN a.ordermonth AND b.ordermonthGROUP BY a.ordermonth,b.ordermonth;

更多关于MySQL相关内容感兴趣的读者可查看本站专题：《MySQL查询技巧大全》、《MySQL常用函数大汇总》、《MySQL日志操作技巧大全》、《MySQL事务操作技巧汇总》、《MySQL存储过程技巧大全》及《MySQL数据库锁相关技巧汇总》

希望本文所述对大家MySQL数据库计有所帮助。

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