Multiple Column Pivot in T-SQL - sql-server

Question

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

Answer 1

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

Answer 2

The trick to doing multiple pivots over a row_number is to modify that row number sequence to store both the sequence and the field number. Here's an example that does what you want with multiple PIVOT statements.
-- populate some test data
if object_id('tempdb..#tmp') is not null drop table #tmp
create table #tmp (
ID int identity(1,1) not null,
MainField varchar(100),
ThatField int,
ThatOtherField datetime
)
insert into #tmp (MainField, ThatField, ThatOtherField)
select 'A', 10, '1/1/2000' union all
select 'A', 20, '2/1/2000' union all
select 'A', 30, '3/1/2000' union all
select 'B', 10, '1/1/2001' union all
select 'B', 20, '2/1/2001' union all
select 'B', 30, '3/1/2001' union all
select 'B', 40, '4/1/2001' union all
select 'C', 10, '1/1/2002' union all
select 'D', 10, '1/1/2000' union all
select 'D', 20, '2/1/2000' --union all
-- pivot over multiple columns using the 1.1, 1.2, 2.1, 2.2 sequence trick
select
MainField,
max([1.1]) as ThatField1,
max([1.2]) as ThatOtherField1,
max([2.1]) as ThatField2,
max([2.2]) as ThatOtherField2,
max([3.1]) as ThatField3,
max([3.2]) as ThatOtherField3,
max([4.1]) as ThatField4,
max([4.2]) as ThatOtherField4
from
(
select x.*,
cast(row_number() over (partition by MainField order by ThatField) as varchar(2)) + '.1' as ThatFieldSequence,
cast(row_number() over (partition by MainField order by ThatField) as varchar(2)) + '.2' as ThatOtherFieldSequence
from #tmp x
) a
pivot (
max(ThatField) for ThatFieldSequence in ([1.1], [2.1], [3.1], [4.1])
) p1
pivot (
max(ThatOtherField) for ThatOtherFieldSequence in ([1.2], [2.2], [3.2], [4.2])
) p2
group by
MainField

Answer 3

I am unsure if you are using MS SQL Server, but if you are... You may want to take a look at the CROSS APPLY functionality of the engine. Basically it will allow you to apply the results of a table-valued UDF to a result set. This would require you to put your pivot query into a table-valued result set.
http://weblogs.sqlteam.com/jeffs/archive/2007/10/18/sql-server-cross-apply.aspx

Answer 4

wrap your sql statement with something like:
select a.segment, sum(field2), sum(field3)
from (original select with case arguments) a
group by a.segment
It should collapse your results into one row, grouped on field1.

Answer 5

It is possible to pivot on multiple columns, but you need to be careful about reusing the pivot column across multiple pivots. Here is a good blog post on the subject:
http://pratchev.blogspot.com/2009/01/pivoting-on-multiple-columns.html