将行数据透视并计入列[重复]

Question

我有如下两列数据：

Client	Type
A	Pencil
A	Ruler
A	Pen
B	Pencil
B	Ruler
C	Pencil
C	Pen

我想旋转“类型”并将它们设为列并按“客户”分组。结果如下所示：

Client	Count(Pencil)	Count(Ruler)	Count(Pen)
A	1	1	1
B	1	1	0
C	1	0	1

如何在 SQL Server 上实现这一点？

谢谢

Answer 1

在 SQL Server 中，您可以将其表示为：

select client,
       sum(case when type = 'Pencil' then 1 else 0 end) as pencil,
       sum(case when type = 'Ruler' then 1 else 0 end) as ruler,
       sum(case when type = 'Pen' then 1 else 0 end) as pen
from t
group by client;

Answer 2

请参考MSDN。

SELECT Client, [Pencil], [Ruler], [Pen]
FROM  
(
  SELECT Client, Type
  FROM tableName
) AS SourceTable  
PIVOT  
(  
  count(Type)  
  FOR Type IN ([Pencil], [Ruler], [Pen])  
) AS PivotTable;