DB2 10.5 for Linux, UNIX, and Windows
Introduction to querying XML data with SQL
XML data can be queried using an SQL fullselect or with the SQL/XML query functions of XMLQUERY and XMLTABLE. The XMLEXISTS predicate can also be used in SQL queries on XML data.
When querying XML data using only SQL, without any XQuery, you can query only at the column level by issuing a fullselect. For this reason, only entire XML documents can be returned from the query; it is not possible to return fragments of a document using only SQL.
To query within XML documents, you need to use XQuery. XQuery can be invoked
from SQL using any of the following SQL/XML functions or predicate:
- XMLQUERY
- An SQL scalar function that returns the result of an XQuery expression as an XML sequence.
- XMLTABLE
- An SQL table function that returns the result of an XQuery expression as a table.
- XMLEXISTS
- An SQL predicate that determines whether an XQuery expression returns a non-empty sequence.