PIVOT / UNPIVOT in SQL Server 2008

Question

I got child / parent tables as below.

MasterTable:

MasterID, Description

ChildTable

ChildID, MasterID, Description.         


        

Answer 1

It greatly depends on whether the number of crosstabbed columns is fixed. If they are, then you can simply do something like:

Select ParentDesc
    , [1] As ChildId1
    , [Description1] As ChildDescription1
    , [2] As ChildId2
    , [Description2] As ChildDescription2
    , [3] As ChildId3
    , [Description3] As ChildDescription3
From    (
        Select C.Id As ChildId, C.Description As ChildDesc, P.Description As ParentDesc
        From ChildItems As C
            Join ParentItems As P
                On P.Id = C.ParentId
        ) As C
Pivot   (
        Count(ChildId)
        For ChildId In([1],[2],[3])
        ) As PVT0
Pivot   (
        Count(ChildDesc)
        For ChildDesc In([Descripion1],[Descripion2],[Descripion3])
        ) As PVT1

There is also a way of achieving similar results use CASE functions.

However, if what you want is to have the number of crosstab columns determined at runtime, then the only means to do that inside of SQL Server is to use some fugly dynamic SQL. This is outside the realm of SQL Server's primary purpose which is to serve up data (as opposed to information). If you want a dynamic crosstab, I would recommend not doing it in SQL Server but instead use a reporting tool or build your result set in a middle-tier component.