SQL Server 2005，年初至今每月计数，按供应商分组，并在结果中包含计数为零时

我有一个问题，我正在计算任何给定客户每月的年初至今报告的不同索赔数量。但我发现，如果客户在这一年中没有任何索赔（因此每个月应显示为0），那么客户根本不会出现在结果集中。我需要客户端显示当月的“0”计数。有人知道怎么做吗？谢谢你的帮助！：）

我的查询类似于：

Select c.client_name,
   SUM(CASE DATEPART(MONTH,c2.DateField)WHEN 1 THEN 1 ELSE 0 END) AS [Jan-13],
   SUM(CASE DATEPART(MONTH,c2.DateField)WHEN 2 THEN 1 ELSE 0 END) AS [Feb-13],
   SUM(CASE DATEPART(MONTH,c2.DateField)WHEN 3 THEN 1 ELSE 0 END) AS [Mar-13] etc.....
   From Client c (Nolock)
          inner join claim c2 (nolock)
          on c.client_id = c2.client_id
   Where c.client_id IN (1,3,4,5,7) AND
   c2.DateField between '001-01-2013' and Getdate()
   GROUP BY c.client_name
   ORDER BY c.Client_name

我的结果如下：

Client Name|Jan-13|Feb-13|Mar-13|etc.....
abc company|12    |17    |0     |etc......
zzz company|3     |0     |15    |etc...

Client Name|Jan-13|Feb-13|Mar-13|etc.....
abc company|12    |17    |0     |etc......
rad company|0     |0     |0     |etc.....
zzz company|3     |0     |15    |etc...

我需要的结果如下所示：

Client Name|Jan-13|Feb-13|Mar-13|etc.....
abc company|12    |17    |0     |etc......
zzz company|3     |0     |15    |etc...

Client Name|Jan-13|Feb-13|Mar-13|etc.....
abc company|12    |17    |0     |etc......
rad company|0     |0     |0     |etc.....
zzz company|3     |0     |15    |etc...

---

您正在使用

内部联接

，它将仅在索赔表中存在匹配记录时才返回客户表中的记录，并将其替换为

左侧外部联接

，它将根据WHERE子句和索赔表列中的联接提供客户表中的所有记录

此查询将加入，然后进行筛选

Select c.client_name,
   SUM(CASE DATEPART(MONTH,c2.DateField)WHEN 1 THEN 1 ELSE 0 END) AS [Jan-13],
   SUM(CASE DATEPART(MONTH,c2.DateField)WHEN 2 THEN 1 ELSE 0 END) AS [Feb-13],
   SUM(CASE DATEPART(MONTH,c2.DateField)WHEN 3 THEN 1 ELSE 0 END) AS [Mar-13] 
   etc.....
   From Client c (Nolock)
          left outer join claim c2 (nolock)
          on c.client_id = c2.client_id
   Where c.client_id IN (1,3,4,5,7) AND
   ( c2.DateField between '01-01-2013' and Getdate() OR c2.DateField IS NULL )
   GROUP BY c.client_name
   ORDER BY c.Client_name

或者此查询将在以下情况之前筛选索赔行——

Select c.client_name,
   SUM(CASE DATEPART(MONTH,c2.DateField)WHEN 1 THEN 1 ELSE 0 END) AS [Jan-13],
   SUM(CASE DATEPART(MONTH,c2.DateField)WHEN 2 THEN 1 ELSE 0 END) AS [Feb-13],
   SUM(CASE DATEPART(MONTH,c2.DateField)WHEN 3 THEN 1 ELSE 0 END) AS [Mar-13] 
   etc.....
   From Client c (Nolock)
          left outer join claim c2 (nolock)
          on c.client_id = c2.client_id 
              AND c2.DateField between '01-01-2013' and Getdate()
   Where c.client_id IN (1,3,4,5,7)
   GROUP BY c.client_name
   ORDER BY c.Client_name

这可能有用

Select
    c.client_name,
    Sum(Case Month(c2.DateField) When 1 Then 1 Else 0 End) As [Jan-13],
    Sum(Case Month(c2.DateField) When 2 Then 1 Else 0 End) As [Feb-13],
    Sum(Case Month(c2.DateField) When 3 Then 1 Else 0 End) As [Mar-13],...
From 
    Client c With (Nolock)
        left outer join 
    Claim c2 With (nolock)
        On c.client_id = c2.client_id And
           c2.DateField between '01-01'2013' and GetDate() -- putting it here makes the outer join apply after the filter
Where 
    c.client_id IN (1,3,4,5,7)
Group By
    c.client_name
Order By 
    c.Client_name

---

否则，您需要在筛选声明的子查询上保留外部联接。无论哪种方法，诀窍都是确保在外部表上的筛选器之后应用左外部联接。

非常感谢@Lobo，我也尝试了左外部联接，但仍然无法获得该年零记录的客户机。这两位失踪的客户没有2013年的任何记录，因此没有任何记录可查。但我仍然需要每个月显示0（@Montwill我更改了查询。如果没有索赔行，

DateField

将为空。