MySQL - 按月查找前 10 条记录

Question

我将介绍表结构：

revshare r : 包含购买信息，包括订单号、销售额、佣金、itemid、EventDate

Products p：包含产品的相关信息，包括 PID（产品 ID），用于加入 Merchants 表以获取 Merchant 信息。

Merchants m：包含有关购买产品的商家的信息，包括 MerchantName

问题

我正在尝试创建一个 MySQL 查询，以根据给定月份的佣金总和拉取前 10 个 itemid。我想获得的整个数据集是从 2011 年到 2013 年，因此每年将填充 120 条记录（每月 10 条）。

我创建了一个查询来提取 1 个月的数据，并计划使用 UNION ALL 来创建一个记录列表，其中包含来自每个查询的 10 条记录（每个单独的查询代表一个月的前 10 个 itemid）。

查询1

此查询根据给定月份期间这些项目的总佣金准确地返回我前 10 个 itemid。

SELECT 
m.MerchantName, 
Count(r.OrderNo), 
sum(r.commission)

FROM revshare r
LEFT JOIN Products p ON r.itemid = p.PID
LEFT JOIN Merchants m ON p.MID = m.MID

WHERE r.EventDate between '2011-01-01' and '2011-01-31'

GROUP by r.itemid
ORDER by 3 DESC LIMIT 10

当我尝试将此查询与另一个查询 UNION 以获取下个月在 '2011-02-01' 和 '2011-02-31' 之间的记录时，我收到错误消息“错误：UNION 和ORDER BY" 我知道这是因为显然您不能在除最后一个之外的任何 UNION 查询集上使用 ORDER BY。我可以提取整个数据集，然后使用 Excel 或 Pentaho BI 仅显示前 10 名，但基于 revshare 表中的庞大数据集，这效率不高。

以下是 UNION ALL 不起作用的查询。有没有人有更好的方法来提取这些数据？

非常感谢任何帮助。

问候， -克里斯

查询 2（由于 ORDER BY 语句而不起作用）

SELECT 
m.MerchantName, 
Count(r.OrderNo), 
sum(r.commission)

FROM revshare r
LEFT JOIN Products p ON r.itemid = p.PID
LEFT JOIN Merchants m ON p.MID = m.MID

WHERE r.EventDate between '2011-01-01' and '2011-01-31'

GROUP by r.itemid
ORDER by 3 DESC LIMIT 10

UNION ALL

SELECT 
m.MerchantName, 
Count(r.OrderNo), 
sum(r.commission)

FROM revshare r
LEFT JOIN Products p ON r.itemid = p.PID
LEFT JOIN Merchants m ON p.MID = m.MID

WHERE r.EventDate between '2011-02-01' and '2011-02-31'

GROUP by r.itemid
ORDER by 3 DESC LIMIT 10

Answer 1

好的，试试这个....

SELECT * FROM (
  SELECT 
    m.MerchantName, 
    Count(r.OrderNo), 
    sum(r.commission)
  FROM
    revshare r
    LEFT JOIN Products p ON r.itemid = p.PID
    LEFT JOIN Merchants m ON p.MID = m.MID
  WHERE
    r.EventDate between '2011-01-01' and '2011-01-31'
  GROUP by
    r.itemid
  ORDER by 
    3 DESC LIMIT 10
) AS RESULT1

UNION ALL

SELECT * FROM (
  SELECT 
    m.MerchantName, 
    Count(r.OrderNo), 
    sum(r.commission)
  FROM
    revshare r
    LEFT JOIN Products p ON r.itemid = p.PID
    LEFT JOIN Merchants m ON p.MID = m.MID
  WHERE
    r.EventDate between '2011-02-01' and '2011-02-31'
  GROUP by
    r.itemid
  ORDER by
    3 DESC LIMIT 10
) AS RESULT2

Answer 2

既然你已经开始了unioning 查询的路径，那么这里是正确的方法：

select t.*
from ((SELECT '2011-01' as yyyymm, m.MerchantName, Count(r.OrderNo) as cnt, sum(r.commission) as comm
       FROM revshare r LEFT JOIN
            Products p
            ON r.itemid = p.PID LEFT JOIN
            Merchants m
            ON p.MID = m.MID
       WHERE r.EventDate between '2011-01-01' and '2011-01-31'
       GROUP by r.itemid
       ORDER by comm DESC
       LIMIT 10
      ) union all
      (SELECT '2011-02' as yyyymm, m.MerchantName, Count(r.OrderNo) as cnt, sum(r.commission) as comm
       FROM revshare r LEFT JOIN
            Products p
            ON r.itemid = p.PID LEFT JOIN
            Merchants m
            ON p.MID = m.MID
       WHERE r.EventDate between '2011-02-01' and '2011-02-28'
       GROUP by r.itemid
       ORDER by comm DESC LIMIT 10
      ) union all
      . . .
     ) t
order by 1, comm desc

换句话说，您需要为union all 使用子查询。请注意，我还添加了yyyymm 来标识月份。