EXISTSNODE
Description of the illustration existsnode.gif
EXISTSNODE determines whether traversal of an XML document using a specified path results in any nodes. It takes as arguments the XMLType instance containing an XML document and a VARCHAR2 XPath string designating a path. The optional namespace_string must resolve to a VARCHAR2 value that specifies a default mapping or namespace mapping for prefixes, which Oracle Database uses when evaluating the XPath expression(s).
The namespace_string argument defaults to the namespace of the root element. If you refer to any subelement in Xpath_string, then you must specify namespace_string, and you must specify the "who" prefix in both of these arguments.
See Also:
"Using XML in SQL Statements" for examples that specifynamespace_string and use the "who" prefix.The return value is NUMBER:
-
0 if no nodes remain after applying the XPath traversal on the document
-
1 if any nodes remain
The following example tests for the existence of the /Warehouse/Dock node in the XML path of the warehouse_spec column of the sample table oe.warehouses:
SELECT warehouse_id, warehouse_name
FROM warehouses
WHERE EXISTSNODE(warehouse_spec, '/Warehouse/Docks') = 1;
WAREHOUSE_ID WAREHOUSE_NAME
------------ -----------------------------------
1 Southlake, Texas
2 San Francisco
4 Seattle, Washington