SQL服务器：如何用其余的零值填充稀疏数据？

Question

我有数据报告每个月和每个客户的销售额。当我对这些值进行计数时，由于 sparsa 数据格式，不会报告零值。

假设客户1-4。假设只有客户 1-2 有录音。 Straight table 在行上有客户 ID，在列上有月份，这样

|CustomerID|MonthID|Value|
-------------------------|
|     1    |201101 |  10 |
|     2    |201101 | 100 |

然后以交叉表格式报告它们

|CustomerID|201101|201102|2011103|...|201501|
---------------------------------------------
|    1     |  10  |   0  |   0   |...|  0   |  
|    2     |  100 |   0  |   0   |...|  0   |
|    3     |  0   |   0  |   0   |...|  0   |
|    4     |  0   |   0  |   0   |...|  0   |

当我计算这个时，我没有得到客户 3-4 的任何信息，因为他们没有录音。我想得到丢失的零行。如何填充或 select 原始数据并将不存在的零值填充到 selection？或者更简短：

处理稀疏数据格式并在最终报告中仍然有零客户的最优雅方法是什么？

Answer 1

在转向交叉表格式之前，您会 cross join tables Customers 和 Months，然后 left join table Sales 到那个。

select 
    c.CustomerId
  , m.MonthId
  , Value = isnull(s.Value,0)
from customers c
  cross join months m
  left join sales s
    on s.CustomerId = c.CustomerId
   and s.MonthId = m.MonthId

rextester 演示：http://rextester.com/XKU62242

returns:

+------------+---------+-------+
| CustomerId | MonthId | Value |
+------------+---------+-------+
|          1 |  201101 |    10 |
|          2 |  201101 |   100 |
|          3 |  201101 |     0 |
|          4 |  201101 |     0 |
|          1 |  201102 |     0 |
|          2 |  201102 |     0 |
|          3 |  201102 |     0 |
|          4 |  201102 |     0 |
|          1 |  201103 |     0 |
|          2 |  201103 |     0 |
|          3 |  201103 |     0 |
|          4 |  201103 |     0 |
+------------+---------+-------+

向上面添加动态 pivot() 可以像这样完成：

declare @cols nvarchar(max);
declare @sql  nvarchar(max);

select @cols = stuff((
    select ',' + quotename(MonthId)
    from months 
    order by MonthId
    for xml path (''), type).value('.','nvarchar(max)')
  ,1,1,'');

select @sql = '
select CustomerId, ' + @cols + '
from (
    select 
        c.CustomerId
      , m.MonthId
      , Value = isnull(s.Value,0)
    from customers c
      cross join months m
      left join sales s
        on s.CustomerId = c.CustomerId
      and s.MonthId = m.MonthId
    ) as t
pivot (sum([Value]) for [MonthId] in (' + @cols + ') ) p';

select @sql as CodeGenerated;
exec sp_executesql @sql;

returns:

+-----------------------------------------------------------------------+
|                             CodeGenerated                             |
+-----------------------------------------------------------------------+
| select CustomerId, [201101],[201102],[201103]                         |
| from (                                                                |
|     select                                                            |
|         c.CustomerId                                                  |
|       , m.MonthId                                                     |
|       , Value = isnull(s.Value,0)                                     |
|     from customers c                                                  |
|       cross join months m                                             |
|       left join sales s                                               |
|         on s.CustomerId = c.CustomerId                                |
|       and s.MonthId = m.MonthId                                       |
|     ) as t                                                            |
| pivot (sum([Value]) for [MonthId] in ([201101],[201102],[201103]) ) p |
+-----------------------------------------------------------------------+

和 exec returns:

+------------+--------+--------+--------+
| CustomerId | 201101 | 201102 | 201103 |
+------------+--------+--------+--------+
|          1 |     10 |      0 |      0 |
|          2 |    100 |      0 |      0 |
|          3 |      0 |      0 |      0 |
|          4 |      0 |      0 |      0 |
+------------+--------+--------+--------+

SQL服务器：如何用其余的零值填充稀疏数据？

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