EXTRACT (XML)

Note:

The EXTRACT (XML) function is deprecated. It is still supported for backward compatibility. However, Oracle recommends that you use the XMLQUERY function instead. See XMLQUERY for more information.

Syntax

extract_xml::=

Description of the illustration extract_xml.eps

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, then the context of the relative path defaults to the root node. The optional namespace_string is required if the XML you are handling uses a namespace prefix. This argument 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
  ORDER BY warehouse_name;

WAREHOUSE_NAME            Number of Docks
------------------------- -------------------------
New Jersey
San Francisco             <Docks>1</Docks>
Seattle, Washington       <Docks>3</Docks>
Southlake, Texas          <Docks>2</Docks>

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