mysql mysql怎么按照自己定义的周统计每周的数据

假设你的表为 ta 日期字段是 dt

那么，以 2015-01-01为起始日，每5天累总计数为:

select datediff(dt, '2015-01-01') div 5 as d5 , count(*)

from ta

group by (datediff(dt, '2015-01-01') div 5)

统计数据库内一周数据时用到 yearweek 函数，查询出来的结果与预期值有较大差距， 原来mysql默认 周日当做一周开始，修改成周一当做开始需要在yearweek函数后的model里面填值1即可

易客CRM之前的版本中有一个报表是按月统计销售情况，最近有个客户想按周统计销售情况。按月统计的Sql语句比较好写，sql语句如下：

SELECT DATE_FORMAT(ec_salesorder.duedate,’%Y-%m’) as m, sum(ec_salesorder.total) as total, count(*) as so_count FROM ec_salesorder GROUP BY m ORDER BY m，也就是把duedate日期以月的形式显示，然后groupby，那么按周如何统计呢？

搜了一下mysql的manual，在这里找到一个解决方法，通过mysql的week函数来做，sql语句如下：SELECT WEEK(ec_salesorder.duedate) as m, sum(ec_salesorder.total) as total, count(*) as so_count FROM ec_salesorder GROUP BY m ORDER BY m，这个方法有个缺陷，不能显示年份，仅仅靠一个周数不方便查看统计信息。

继续研究mysql manual，在DATE_FORMAT函数介绍发现2个格式符和周有点关系：

%X Year for the week where Sunday is the first day of the week, numeric, four digitsused with %V

%x Year for the week, where Monday is the first day of the week, numeric, four digitsused with %v

把上面的Sql语句中改成：

SELECT DATE_FORMAT(ec_salesorder.duedate,’%x %v’) as m, sum(ec_salesorder.total) as total, count(*) as so_count FROM ec_salesorder GROUP BY m ORDER BY m

显示的结果如下：

m total so_count

2009 11 10000.00 3

2009 12 44000.00 5

如果周日为一周的第一天，那么sql语句应该为:

SELECT DATE_FORMAT(ec_salesorder.duedate,’%X %V’) as m, sum(ec_salesorder.total) as total, count(*) as so_count FROM ec_salesorder GROUP BY m ORDER BY m

结果应该没错，不出意外，易客CRM下个版本将增加按周统计销售情况的报表。

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