Question

I have a SQL Server 2005 table like this:

create table Taxonomy( CategoryId integer primary key, ParentCategoryId integer references Taxonomy(CategoryId), CategoryDescription varchar(50)  ) 

with data looking like CategoryIdParentCategoryIdCategoryDescription 123nullfoo345123bar

I'd like to query it into an xml document like this:

<taxonomy> <category categoryid='123' categorydescription='foo'>       <category id='455' categorydescription='bar'/> </category> </taxonomy> 

Is it possible to do this with FOR XML AUTO, ELEMENTS? Or do I need to use FOR XML EXPLICIT?

Answer 1

It is possible but the main limitation is that the levels of the hierarchy must be hard coded. The SQL Server Books Online has a description of how to represent hierarchies in XML at this link. Below is a sample query that produces the XML you requested:

SELECT [CategoryId] as '@CategoryID'       ,[CategoryDescription] as '@CategoryDescription'       ,(SELECT [CategoryId]        ,[CategoryDescription]        FROM [dbo].[Taxonomy] 'Category'        WHERE ParentCategoryId = rootQuery.CategoryId        FOR XML AUTO, TYPE) FROM [dbo].[Taxonomy] as rootQuery where [ParentCategoryId] is null FOR XML PATH('Category'), ROOT('Taxonomy')