MS SQL Server pivot table with subquery in column clause - sql

Question

Im sure this is a simple technique although I can't find an answer so far!
I have
TIMESTAMP | POINTNAME | VALUE
2012-10-10 16:00:00 AHU01 20
2012-10-10 16:00:00 AHU02 25
2012-10-10 16:00:15 AHU01 26
2012-10-10 16:00:15 AHU02 35
etc... ( for approx 800 POINTNAMES)
with many pointnames I dont want to list each one in the 'IN' clause of the pivot 'FOR'
(as syntax given below) definition but would like to use perhaps a subquery.
So what I would like is all the POINTNAME values as columns with A TIMESTAMP AND VALUE column, so I will get one TIMESTAMP value and many columns with each POINTNAME, there is only one value per POINTNAME PER TIMESTAMP so I don't need to aggregate anything so just choose max anyway?
Something like:
SELECT [TIMESTAMP] FROM ( SELECT * FROM POINT_TABLE)
PIVOT( Max[Value] FOR [POINTNAME] IN (SELECT DISTINCT [POINTNAME] FROM POINT_TABLE)
would produce-
TIMESTAMP AHU01 AHU02
2012-10-10 16:00:00 20 25
2012-10-10 16:15:00 26 35
I realise it is probably no this simple but hopefully you get what I'm trying to achieve?
PIVOT SYNTAX:
SELECT <non-pivoted column>,
[first pivoted column] AS <column name>,
[second pivoted column] AS <column name>,
...
[last pivoted column] AS <column name>
FROM
(<SELECT query that produces the data>)
AS <alias for the source query>
PIVOT
(
<aggregation function>(<column being aggregated>)
FOR
[<column that contains the values that will become column headers>]
IN ( [first pivoted column], [second pivoted column],
... [last pivoted column])
) AS <alias for the pivot table>
<optional ORDER BY clause>;

Answer 1

for dynamic number of columns you have to use dynamic SQL
declare
#cols nvarchar(max),
#stmt nvarchar(max)
select #cols = isnull(#cols + ', ', '') + '[' + T.POINTNAME + ']' from (select distinct POINTNAME from TABLE1) as T
select #stmt = '
select *
from TABLE1 as T
pivot
(
max(T.VALUE)
for T.POINTNAME in (' + #cols + ')
) as P'
exec sp_executesql #stmt = #stmt
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