Name
XMLType.extract — Evaluates given XPATH expression.
Synopsis
XMLType.extract ( |
in xpath_expn varchar , |
in namespace_map varchar
); |
Description
The member function calculates the given XPATH expression
xpath_expn using the XML
entity of the instance as a context node. If a namespace_map parameter is given then
the function adds namespace declarations from this parameter into
the beginning of xpath_expn
before the evaluation. The function returns the first result of the
XPATH evaluation or NULL if there are no results. If the result is
an XML entity then it is converted into a non-schema based instance
of XMLType.
Parameters
xpath_expn
A text of XPATH expression to evaluate.
namespace_map
A string that is a list of namespace prefix declarations
delimited by whitespace characters. If the xpath_expn expression also contains a
list of declarations then these two lists are concatenated.
Return Types
The function returns a non-schema based XMLType instance, NULL or a value of any other type
Examples
Example24.548.A table with an XMLType column
This populates a table with XML data and then selects 'ename' element from the appropriate record.
create table TEST_XMLS (I integer primary key, XMLVAL XMLType);
insert into TEST_XMLS values (1, XMLType('<emp><empno>221</empno><ename>John</ename></emp>'));
insert into TEST_XMLS values (2, XMLType('<po><pono>331</pono><poname>PO_1</poname></po>'));
insert into TEST_XMLS values (3, XMLType('<oil-rig
xml:id="14a_01" water="0.413"/><oil-rig
xml:id="14b_01" water="0.402"/>'));
select e.XMLVAL.extract ('//ename').getCLobVal() as ENAME
from TEST_XMLS as e
where e.XMLVAL.existsNode('/emp/empno')
ENAME
NVARCHAR
_______________________________________________________________________________
<ename>John</ename>
1 Rows. -- 00000 msec.