Question

我有一个SQL表（Email_Campaigns），其中包含我们运行的广告系列的主列表：

Name            DateSent
Campaign01    01/01/2011
Campaign02    01/15/2011
..
Campaign40    10/01/2011

我有一个客户列表（Email_Received）及其会员编号和他们收到的广告系列：

PK    MembershipNo    CampaignName
1           123456      Campaign01
2           123456      Campaign02
3           987654      Campaign05
4           111111      Campaign10

我还获得了客户MembershipNo（客户）的主列表

问题：如何编写查询以列出每个广告系列，并计算未收到该电子邮件的客户数量？例如（'Received'列仅在此处显示以供参考，因为我知道如何计算，因此不是必需的）：

Name          Received    DidNotReceive
Campaign01        1000             9000
Campaign02        3000             7000
..
Campaign40         100             9900

Answer 1

这是一种标准的SQL编写方式：

SELECT ec.Name, count(c.MembershipNo) AS DidNotReceive
  FROM Customers AS c
     , Email_Campaigns AS ec
 WHERE NOT EXISTS (
    SELECT 1
      FROM Email_Received AS r
     WHERE er.CampaignName = ec.CampaignName
       AND er.MembershipNo = c.MembershipNo)
 GROUP BY ec.Name
 ORDER BY ec.Name;

Answer 2

SELECT er.CampaignName, 
       COUNT(*) AS Received, 
       (SELECT COUNT(*) FROM Customers) - COUNT(*) AS DidNotReceive
    FROM Email_Received er
    GROUP BY er.CampaignName
    ORDER BY er.CampaignName;

这是最简单的水平。可能需要考虑其他因素，例如在分发广告系列时是否有特定客户处于活动状态。

查询分组依据并从多个列表中排除

2 个答案: