T-SQL 中的多列透视 [英] Multiple Column Pivot in T-SQL

问题描述

我正在处理一个表格，其中有多行需要转入列.因此，枢轴是解决此问题的完美解决方案，并且当我只需要一个字段时效果很好.我需要根据枢轴返回几个字段.这是去除了细节的伪代码:

I am working with a table where there are multiple rows that I need pivoted into columns. So the pivot is the perfect solution for this, and works well when all I need is one field. I am needing to return several fields based upon the pivot. Here is the pseudo code with specifics stripped out:

SELECT 
  field1,
  [1], [2], [3], [4]
FROM
  (
  SELECT 
    field1, 
    field2, 
    (ROW_NUMBER() OVER(PARTITION BY field1 ORDER BY field2)) RowID
  FROM tblname
  ) AS SourceTable
PIVOT
  (
  MAX(field2)
  FOR RowID IN ([1], [2], [3], [4])
  ) AS PivotTable;

上述语法非常有效，但是当我需要获取 field3、field4..... 中的其他信息时该怎么办?

The above syntax works brilliantly, but what do I do when I need to get additional information found in field3, field4....?

推荐答案

使用 MAX(CASE...) 和 GROUP BY 重写:

Rewrite using MAX(CASE...) and GROUP BY:

select 
  field1
, [1] = max(case when RowID = 1 then field2 end)
, [2] = max(case when RowID = 2 then field2 end)
, [3] = max(case when RowID = 3 then field2 end)
, [4] = max(case when RowID = 4 then field2 end)
from (
  select 
    field1
  , field2
  , RowID = row_number() over (partition by field1 order by field2)
  from tblname
  ) SourceTable
group by 
  field1

从那里您可以添加 field3、field4 等.

From there you can add in field3, field4, etc.

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