mysql - MySQL表数据如何按半年聚合？

Question

有人可以帮我写一个 MySQL 查询来根据半年划分数据吗？有日期格式列的记录？

我按每月和每季度为 GROUP 编写了查询，但半年没有发生。

我对每周、每月和每季度使用了以下查询:

CREATE view darren_inventory_mrp_forecast_summary as
    ( SELECT row_number() OVER(ORDER BY sub.product_id) as id,
             SUM(sub.quantity)/12 as quantity,
             SUM(sub2.quantity)/4 as quarterly,
             SUM(sub3.quantity)/51 as weekly,
             sub.product_id as product_id FROM
          (SELECT row_number() OVER(ORDER BY product_id) as id,
                  product_id as product_id,
                  SUM(product_qty) as quantity
          FROM stock_move
          WHERE consumed_for IS NOT NULL
          GROUP BY to_char(DATE(create_date), 'YYYY-MM'), product_id 
          ) 
      as sub 
      LEFT JOIN 
          (SELECT row_number() OVER(ORDER BY product_id) as id,
                  product_id as product_id,
                  SUM(product_qty) as quantity
          FROM stock_move
          WHERE consumed_for IS NOT NULL
          GROUP BY to_char(DATE(create_date), 'YYYY-Q'), product_id 
          ) 
      as sub2 on (sub2.product_id=sub.product_id)  
      LEFT JOIN
          (SELECT row_number() OVER(ORDER BY product_id) as id,
                  product_id as product_id,
                  SUM(product_qty) as quantity
          FROM stock_move
          WHERE consumed_for IS NOT NULL
          GROUP BY to_char(DATE(create_date), 'YYYY-WW'), product_id 
          ) 
      as sub3 on (sub3.product_id=sub.product_id)  
      GROUP BY sub.product_id
    )

Answer 1

您可以使用此获取日期项出现的月份的第一天。

select last_day(datecolumn) + interval 1 day - interval 1 month 

你可以用这个获取日期项目的月份

select month(datecolumn)

你可以像这样得到半年的月数(0-5)

select (month(datecolumn) -1) mod 6

所以，你可以这样得到半年的第一天。

select last_day(datecolumn) + interval 1 day - interval 1 month
        - interval (month(datecolumn) -1) mod 6 month

然后您可以 GROUP BY 这个大表达式并以这种方式汇总您的数据。

这也有效:

select last_day(datecolumn) + interval 1 day - interval 1 month
      - interval (quarter(datecolumn) -1) mod 2 quarter

诀窍是想出一个表达式，将任何日期时间表达式截断到它所在的半年的第一天。

如果你只想处理特定年份的东西，做这样的事情。

  WHERE datecolumn >= DATE_FORMAT(NOW(), '%y-01-01') - INTERVAL 1 YEAR
    AND datecolumn >  DATE_FORMAT(NOW(), '%y-01-01') + INTERVAL 1 YEAR

此特定示例选择日历年 2015 和 2016 中的所有内容。表达式 DATE_FORMAT(someTimestampValue, '%y-01-01') 将日期或日期时间值截断到日历的开头年。