T-SQL中的多列数据透视

Question

我正在使用一个表,其中有多行需要转换为列.所以枢轴是这个的完美解决方案,并且当我需要的只是一个领域时效果很好.我需要根据枢轴返回几个字段.这是伪代码,其中删除了细节:

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;

上面的语法非常出色,但是当我需要获取field3,field4中的其他信息时,我该怎么办？

Answer 1

使用MAX(CASE ...)和GROUP BY重写:

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

从那里你可以添加field3,field4等.