EXTRACT (XML)

Syntax

extract_xml::=

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Description of the illustration extract_xml.gif

Purpose

EXTRACT (XML) is similar to the EXISTSNODE function. It applies a VARCHAR2 XPath string and returns an XMLType instance containing an XML fragment. You can specify an absolute XPath_string with an initial slash or a relative XPath_string by omitting the initial slash. If you omit the initial slash, the context of the relative path defaults to the root node. 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).

Examples

The following example extracts the value of the /Warehouse/Dock node of the XML path of the warehouse_spec column in the sample table oe.warehouses:

SELECT warehouse_name, EXTRACT(warehouse_spec, '/Warehouse/Docks')
 "Number of Docks"
 FROM warehouses
 WHERE warehouse_spec IS NOT NULL;
WAREHOUSE_NAME Number of Docks
-------------------- --------------------
Southlake, Texas <Docks>2</Docks>
San Francisco <Docks>1</Docks>
New Jersey <Docks/>
Seattle, Washington <Docks>3</Docks>

Compare this example with the example for EXTRACTVALUE, which returns the scalar value of the XML fragment.