SQL Dynamic Pivot - how to order columns

Question

I'm working on a dynamic pivot query on a table that contains:

• OID - OrderID
• Size - size of the product
• BucketNum - the order that the sizes should go
• quantity - how many ordered

The size column contains different sizes depending upon the OID.

So, using the code found here, I put this together:

DECLARE @listCol VARCHAR(2000)
DECLARE @query VARCHAR(4000)

SELECT  @listCol = STUFF(( SELECT distinct  '], [' + [size]
                           FROM     #t
                         FOR
                           XML PATH('')
                         ), 1, 2, '') + ']'


SET @query = 'SELECT * FROM
      (SELECT OID,  [size], [quantity]
            FROM #t 
            ) src
PIVOT (SUM(quantity) FOR Size
IN (' + @listCol + ')) AS pvt'


EXECUTE ( @query )

This works great except that the column headers (the sizes labels) are not in the order based upon the bucketnum column. The are in the order based upon the sizes.

I've tried the optional Order By after the pivot, but that is not working.

How do I control the order in which the columns appear?

Thank you

Solution 1

You need to fix this:

SELECT  @listCol = STUFF(( SELECT distinct  '], [' + [size]
                           FROM     #t
                         FOR
                           XML PATH('')
                         ), 1, 2, '') + ']'

To return the columns in the right order. You might have to do something like this instead of using DISTINCT:

SELECT [size]
FROM     #t
GROUP BY [size]
ORDER BY MIN(BucketNum)

Solution 2

SELECT @listCol = STUFF(
        (SELECT DISTINCT ',' + QUOTENAME(size) AS [size]
        FROM #t
        ORDER BY [size]
        FOR XML PATH('')

Comments

[Chris Burgess]

Ahhhhh! The 'MIN(BucketNum)' bit was what I needed!! Thank you, thank you!

[Cade Roux]

That solution is non-dynamic only in names of columns, not in number of columns, which still would need a dynamic technique at the time of the pivot operation. I have used that technique for pivoting variable date ranges however where it's always 12 months, but starts at different months - it's a basic sliding transform.

[JAL]

Although this query may answer the question, can you provide a little more information about how this answer works?

[frustratedInFresno]

It works the same was as the code in the original post but it creates an alias for the column so that it may have an ORDER BY applied to it.