You can store the XML document in the file system (i.e. as a file on the server) and read the data from it by using standard file system functions. Most of the technologies (J2EE, .NET, PHP, CGI/Perl, etc) have in-built libraries to work with XML files.

I have data in database and a lot of data resides as XML files as well. I do not want to maintain different data stores having the data in database and XML data in files. Is there any way to manage both XML and relational data together in a single data store?

If you do not want to store the XML data as files and want to maintain the complete data in a database, you can store the xml document into the database as BLOB or CLOB type. This would store the XML file in the binary format. This approach is recommended only if you want to store or retrieve the XML file in its entirety. But retrieving a specific element/attribute from XML document would have performance constraints as the complete XML document has to be loaded to fetch even a single record.

I am working on an application for data storage which deals mostly with XML data. I am storing the XML data as CLOB data type. Is there any other way to work with XML data?

Storing the XML as CLOB data type has its drawbacks. Searching and retrieving a subset of the document would be slow. The XML document needs to be parsed for each query to determine which portions of the document satisfy the specified search criteria. Furthermore, updating large objects would also take time. Your applications must provide the entire XML document to the DBMS for update, even if it only changed a small portion of it. This can result in unacceptably high processing costs, particularly if the XML document is very large

Are there any other ways to store XML data in database?

Alternatively, you can split the elements and attributes of the XML document to relational columns in one or more tables. Storing the data like this would have several advantages. You can directly work with selected portions of the “converted” XML data. You can add index to columns to make data retrieval more efficient and fast. You can make use of SQL queries to retrieve the required piece of data.

But decomposing the XML would be difficult (some time impossible) if XML documents contain heavily nested parent/child relationships and irregular structures. Shredding such documents may also require a large number of tables. Querying a “shredded” document would require complex SQL statements and it may include many joins. It would take time to write these queries. It will give runtime productivity and performance problems. Moreover, it is very difficult , if not impossible to recover (compose ) the XML document from these relational tables

You can use pureXML (DB2 from IBM) to store the XML data in the database. It stores the XML document natively in the database which means XML is not stored as CLOB or shredded into tables. XML remains XML even inside the database. The data can be queried using SQL or XQuery. Searching and retrieving subsets of XML would be very fast as XML is not parsed during querying.