Writing reports from XML embedded in a CLOB

Question

I need to write some reports using custom data that is stored by a COTS application.  This software supplier stores this custom data in an XML structure and then writes it to a CLOB in the table.  We are using Oracle 9.2.0.6.0 and we have the complete BusinessObjects suite of tools.  I guess I'm not sure of an approach on how to get this information out and onto a report - any suggestions?
Thanks,
Mark

Answer 1

Welcome to the XML side of the world, where you will love it and curse it, just like any other piece of technology.
So as I understand it, the scope of your operation is to extract information from an XML file and then write that information to disk, correct?
Some questions
- Why is the XML stored in a CLOB instead of an XMLType column?  Without knowing the system history, it is a valid question.
- How big are the XML?  The reason I ask this is because when the XML is stored in XMLType columns (of Object Relational structure or SECUREFILE BINARY XML format), then Oracle can parse the XML substantially easier than when it is stored as a CLOB.  If the XML is fairly small, you may see no performance difference between the two.
The Oracle DB itself has no built in ability to generate a schema from an XML file.  In order to do that, you would need to use some third party tool that has that functionality built in.  For example, XML Spy can do this.  Other tools can as well, but that is what came to mind first as it is what I use.  The one thing to remember is that the schema it builds represents that one instance of XML.  Other instances of XML may be different and not validate against the schema you generated, but still have been valid against the unknown original schema.
You can register the schema in the database and then use the XML to create an XMLType instance associated to the schema and then validate the XML that way.  One example can be found at XML DB FAQ and here is another example Re: XML Schema validation
Hope that helps you continue on.