Jeff Kish wrote:
> On Wed, 01 Dec 2004 14:24:45 +0100, Tjerk Wolterink
> <tjerk@w...> wrote:
> 
> 
>>Terry P wrote:
>>
>>>Are there any tools (java classes, tag libraries) which can translate
>>>xpath statements into a SQL query?
>>>
>>>Given an xpath query which has a predicate that filters node values or
>>>attributes, I want help constructing the Where clause of a SQL
>>>statement that will mirror the expressions and functions contained in
>>>the predicate.
>>>
>>>Such a tool may require an XML to DB mapping or it would need to make
>>>assumptions about the structure of the document and the tables.
>>>
>>>Thanks for any advice.
>>>
>>>Terry
>>
>>What sory of database are you talking about?
>>A ordinary relational database? Or an XML-database.
>>Xml-databases are new and not very fast, but there is extensive research in xml-database-system.
>>Those system support xpath and xquery as query languages.
>>
>>I'f you want to map xpath onto sql, then your're right: you need some
>>rules about how xml is mapped onto the relational database.
>>With those rules you could map xpath expression to sql expressions.
>>
>>I don't know wether they exists. I myself have my own mapping rules,
>>rather simplistic rules but it does the job for me.
> 
> I was under the (mistaken?) assumption that eventually xpath will let you
> query multiple data sources, i.e. databases included.
> 
> Is this true?
> Jeff Kish

XPath is a language to query xml documents, or multiple xml documents, it returns a node-set.
It cannot query ordinary relational based databases, i think.

But you can query multiple data-sources [multiple xml files, using the document() function].
And maybe in the future you can also query XML-based databases with XPath,

But xpath is a rather simple query language for xml, XQuery is much more powerfull.