Sql Server 2008 Cross Tab Query

Question

I usually can figure out any sql queries I need for my applications, but I have recently been stumped by a Cross Tab query I need to create and was wondering if you could help?

I have 3 tables

Category(catID, catTitle) 
Equipment(equipID, make, model, quantity, catID, siteID)
Site(siteID, title)

And I would like to create a Cross Tab query to display a result set like below

Category   Site1   Site2   Site3   Site4   Site5
PC           2       0       10      3      6
Camera       12      4       2       0      8
Printer      3       2       1       1      2

The numbers displayed represent a total of each category item within each site using the quantity field withint the Equipment table. I have never had to do a Cross Tab query before and I am struggling to get this working.

Answer 1

You should be able to do this with the 'pivot' operator. Something like this (though I am sure I muffed some spelling or syntax details...):

select catTitle, [1] as site1, [2] as site2, [3] as site3, [4] as site4, [5] as site5
  from (select category.catTitle, equipment.quantity, site.title
          from equipment
            inner join site
              on (equipment.siteid = site.siteid)
            inner join category
              on (category.catid = equipment.catid)
        ) 
  pivot
  (
  sum (quantity)
    for equipment.siteid in ( [1], [2], [3], [4], [5] )
  ) as pvt
order by pvt.category;

The problem with this is that you need to know the exact set of site ids you want to include in the query. If you need a more dynamic crosstab (like you can get in Excel), then you need to generate the query text as a string and use sp_executesql to run it. In the generated text, you include as many of the "[1], [2], [3], [4], [5]..." and "[1] as site1, [2] as site2..." things as you need.