Oracle XML Handling
Transcript of Oracle XML Handling
XML Storage Options:1. VARCHAR2 – unstructured, limited size2. CLOBs – unstructured, max file = 2GB3. XMLType – structured, associate with XDK and other XML
operations
XML DB Architecture:1. XML DB Repository2. DOM fidelity3. SQL* Loader
Using XMLTYPE
XML Piecewise UpdateUpdate part of the xml document in the database specified by the XPath expression.
XML Schema ValidationManually or automatically validate XML documents as they are inserted to the Database.
XML Document GenerationGenerate XML data from database using normal SQL query.
Creating XMLType Column or table with optional XML Schema support
create table profile(pid number,pfile XMLType);
create table profile of XMLType;
create table profile of XMLTypeXMLSCHEMA “http://bumbus.ucdavis.edu/scholar.xsd”ELEMENT “UCLEADS”
Declares XMLType Column
Declares XMLType Table
Not Recommended
Declares XMLType Table conformed to an XML Schema and specific the root element of the xml document to be inserted.
Storing XML document into the databaseinsert into profilevalues(100, XMLType('
<ScholarProfile><ID>1</ID><LastName> Azzzr</LastName><FirstName>Hussain</FirstName><Email>[email protected]</Email><Major>Load Runner</Major><Grade>A</Grade>
</ScholarProfile>‘ ));
Insert the whole XML document in SQL query
Accessing XML data stored as XMLType instance
1. ExtractValue()- access the value of an XML node
2. ExistsNode() - check if a particular node existed
3. Exact() - extract a collection of XML nodes
4. XMLSequence()- converts a fragment of XML into a collection (a table) of XMLType instances.
SELECT extract(X.pfile,'UCLEADS/ScholarProfile/Major')FROM profile X;
Results are returned as a fragment of XML
SELECT extractValue(value(w),'/Major') FROM profile X, TABLE ( xmlsequence (
extract(value(X), '/UCLEADS/ScholarProfile/Major'))) w;
Values are extracted from the nodes of the XMLType table generated using the XMLSequence()
SELECT existsNode(x.pfile, '/UCLEADS/ScholarProfile/Major') SubFound, existsNode(x.pfile, '/UCLEADS/ScholarProfile[Major="ORACLE"]') MajorFound, existsNode(x.pfile, '/UCLEADS/ScholarProfile[Major="Oracle"]') MajorFound2 FROM Profile1 X;
SELECT count(*) FROM Profile X WHERE existsNode(x.pfile, '/UCLEADS/ScholarProfile[Major="Oracle"‘]) = 1;
<EMPLOYEES><EMP>
<EMPNO>112</EMPNO><EMPNAME>Joe</EMPNAME><SALARY>50000</SALARY>
</EMP><EMP>
<EMPNO>217</EMPNO><EMPNAME>Jane</EMPNAME><SALARY>60000</SALARY>
</EMP><EMP>
<EMPNO>412</EMPNO><EMPNAME>Jack</EMPNAME><SALARY>40000</SALARY>
</EMP></EMPLOYEES>
SELECT UPDATEXML(emp_col, '/EMPLOYEES/EMP[EMPNAME="Joe"]/SALARY/text()', 100000,
'//EMP[EMPNAME="Jack"]/EMPNAME/text()','Jackson',
'//EMP[EMPNO=217]', XMLTYPE.CREATEXML('<EMP><EMPNO>217</EMPNO><EMPNAME>Jane</EMPNAME>'))
FROM emp_tab e;
UPDATEXML takes as arguments an XMLType instance and an XPath-value pair and returns an XMLType instance with the updated value
<EMPLOYEES><EMP><EMPNO>112</EMPNO><EMPNAME>Joe</EMPNAME><SALARY>100000</SALARY></EMP><EMP><EMPNO>217</EMPNO><EMPNAME>Jane</EMPNAME></EMP><EMP><EMPNO>412</EMPNO><EMPNAME>Jackson</EMPNAME><SALARY>40000</SALARY></EMP></EMPLOYEES>
<EMPLOYEES><EMP>
<EMPNO>112</EMPNO><EMPNAME>Joe</EMPNAME><SALARY>50000</SALARY>
</EMP><EMP>
<EMPNO>217</EMPNO><EMPNAME>Jane</EMPNAME><SALARY>60000</SALARY>
</EMP><EMP>
<EMPNO>412</EMPNO><EMPNAME>Jack</EMPNAME><SALARY>40000</SALARY>
</EMP></EMPLOYEES>
CREATE VIEW new_emp_viewAS SELECT
UPDATEXML(emp_col, '/EMPLOYEES/EMP/SALARY/text()', 0) emp_view_col
FROM emp_tab e
UPDATE profile t SET value(t) = updateXML(value(t),'/UCLEADS/ScholarProfile/Major/text()','CS') WHERE existsNode(value(t),
'/UCLEADS/ScholarProfile[Major="Computer Science"]') = 1;
XML Piecewise Update
• isFragment() – returns (1) if the XMLType contains XML document fragment.
• getClobVal() – converts the XMLType document into CLOB object.
• getRootElement() – get the root element of the XML document.
• getNameSpace() – get the namespace of the root element of the XML document.
select xmltype(xmltype.getclobVal(t.pfile)).getRootElement() Exmpl1, xmltype.getRootElement(t.pfile)Exmp2, xmltype.isFragment(t.pfile)isFrag1 , xmltype.isFragment(extract(t.pfile,'/UCLEADS/ScholarProfile'))isFrag2 from profile1 t;