SQL/XML for Developers

Lewis Cunningham Data Architect, JP Morgan Chase http://it.toolbox.com/blogs/oracle-guide http://databasewisdom.com/

ODTUG Kaleidoscope 2009 06/21/2009

Introduction • Oracle ACE Director

• Author • Data Architect for JP Morgan Chase

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Developers 3

Agenda 

What is XML?



What is the XMLType data type?



What is SQL/XML?



What should(n’t) I do with XML?

What is XML? 4



What is XML? 5 

Semi-Structured  





Markup “Language”  



Hierarchical Not relational Not freeform

Tags Identify Data Lewis

Human AND machine readable

What is XML? 6 

Elements  



Elements are nodes 

 



Root Element Child Elements

Some nodes contain elements Some nodes contain character data A node can contain both

Namespaces

What is XML? 7 

Well Formed XML 

Follows XML formatting rules 



 



All open tags have closing tags All attribute values are enclosed in quotes

If a document is not well formed, it is not XML A well formed document may not be a VALID document

Valid XML  

Conforms to a specific specification (DTD, XSD, RNG)‫‏‬ A valid document will always be a well formed document

What is XML? 8



Element/Tag

Simple Example

Childnode1 Child to rootnode

Some Data Childnode1 is Sibling to Some more childnode2 data Closing Empty Tag Tag

What is XML? 9

Namespaces 

A namespace prevents naming collisions



A namespace provides clarity



A namespace allows multiple documents to be combined into a single document

What is XML? 10



Simple Example

Namespace Identifier

Namespace Name

Namespace URI

Some Data Some more Namespace data Usage Default Usage

What is XML? 11

Describing XML 

DTD – Document Type Description



XSD – XML Schema



Relax NG – REgular LAnguage for Xml Next Generation

What is XML? 12

DTD      

A list of valid elements and attributes May be inline or external Original descriptive language Limited and mostly obsolete No data type definitions No support for Namespaces

DTD Example 13

]>

What is XML? 14

XSD      

The XML Schema is the W3C replacement to DTDs XSD supports data types an namespaces XML Schemas are defined as XML Allows you to define ordering/number of elements Allows you to define mandatory elements XML Schemas are extensible

XSD Example 15



What is XML? 16

RELAX NG     



XML and non-XML formats Simpler than XSD More like a speaking dialect than an XML dialect Supports data types and namespaces Not as robust as XSD (fewer data types, not as many rules (defaults and such)‫‏‬ Not as widely utilized as XSD

RELAX NG (XML) Example 17



RELAX NG (Compact) Example 18

element patron { element name { text } & element id-num { text } & element book { (attribute isbn { text } | attribute title { text } ) }* }

What is the XMLType data type? 19 

Object Data Type



Clob based



Well formed check



Validating and Non-Validating



May contain XML fragments

What is the XMLType data type? 20 



XML Document data goes here XML Content (fragment)‫‏‬ Lewisyes

What is the XMLType data type? 21 

Declare a column as XML create table xml_tab ( id integer, data XMLType );



Declare a variable as XML DECLARE v_xml XMLType; BEGIN ……

What is SQL/XML? 22

SQL/ XML

What is SQL/XML? 23 

SQL/XML (or SQL/X) is standards based



Combines XML and SQL





IBM, Oracle, Microsoft and Sybase all played a large part in defining SQL/XML Home on the web (but no longer maintained): www.sqlx.org

What is SQL/XML? 24









SQL/XML defines a set of mappings and a set of functions Based on XQuery and XPath Oracle implements the core functions of SQL/XML XQuery is also supported

What is SQL/XML? 

SQL/X Functions        

 

XMLParse XMLSerialize XMLSequence XMLTable XMLElement XMLForest XMLAgg XML Comment XMLConcat More

25

What is SQL/XML? 26



Sample data CREATE TABLE EMP ( LAST_NAME VARCHAR2(50), EMP_ID NUMBER NOT NULL, FIRST_NAME VARCHAR2(50), DEPT_ID NUMBER, SALARY NUMBER, CONSTRAINT EMP_pkey PRIMARY KEY (EMP_ID)‫‏‬ )‫‏‬

What is SQL/XML? Sample sample data:

27

INSERT INTO EMP( LAST_NAME, EMP_ID, FIRST_NAME, DEPT_ID, SALARY)‫‏‬ VALUES ('Blow', 1, 'Joe', 1, 10000); Also INSERT..... ('Head', 2, 'Helmut', 1, 12000), ('Jack', 3, 'Noe', 1, 12000), ('Hard', 4, 'Blow', 2, 20000), ('First', 5, 'Hugo', 2, 21000), ('Spaem',6, 'Kingoof', 2, 20000), ('Ventura', 7, 'Ace', 3, 35000), ('Nickleby', 8, 'Nick', 3, 400000), ('Budd', 9, 'Billy', 4, 99000), ('Cleaver', 10, 'Wally', 4, 100000) ;

What is SQL/XML? - XML Parse 28



The XMLType constructor, or the SQL/XML function XMLParse, will convert text (or clobs) into XML vXMLVar XMLType; vXMLVar := XMLType(‘data’); vXMLVar := XMLParse(DOCUMENT ‘data’);

What is SQL/XML? XMLSerialize 29



XMLSerialize turns XML into text (you can also use XMLType.toString)‫‏‬ vString := XMLSerialize( DOCUMENT v_xml AS VARCHAR2); vString := XMLSerialize( CONTENT v_xml AS CLOB);

What is SQL/XML? XMLElement 30

SELECT XMLElement(name main, last_name) from emp;

Blow Head Jack Hard First

What is SQL/XML? – XMLElement‫‏‬Cont’d 31

SELECT XMLElement(name main, last_name), XMLElement(name main, first_name)‫‏‬ FROM emp; Blow Head Jack Hard

| | | |

Joe Helmut Noe Blow

What is SQL/XML? - XMLForest 32

SELECT XMLForest(last_name, first_name)‫‏‬ FROM emp; BlowJoe HeadHelmut

What is SQL/XML? – XMLForest‫‏‬Cont’d 33

SELECT XMLElement(name main, XMLForest(last_name, first_name) )‫‏‬ FROM emp; Blow Joe Head Helmut

What is SQL/XML? – XMLAgg 34

SELECT XMLAgg( XMLForest(last_name, first_name) )‫‏‬ FROM emp; Blow Joe Head Helmut Jack Noe…

What is SQL/XML? – XMLAgg Cont'd 35

SELECT XMLElement(name main, XMLAgg(XMLForest(last_name, first_name) ))‫‏‬ FROM emp; Blow Joe Head Helmut Jack Noe…

What is SQL/XML? – Concatenating Columns 36

SELECT XMLElement(name main, XMLForest(last_name || ',' || first_name AS fullname, salary) ) FROM emp; Blow,Joe 10000 Head,Helmut 12000

What is SQL/XML? – Concat and Attributes 37

SELECT XMLElement(name main, XMLElement(name fullname, XMLAttributes(dept_id), last_name || ',' || first_name ), XMLForest(salary) ) FROM emp;

Blow,Joe 10000

What is SQL/XML? XMLComment 38

SELECT XMLElement(name main, XMLComment('Comment goes here'), XMLForest(last_name, first_name))‫‏‬ FROM emp; Blow Joe

What is SQL/XML? - XMLConcat 39

SELECT XMLElement(name lastname, last_name), XMLElement(name firstname, first_name)‫‏‬ FROM emp; Blow Joe Head Helmut

What is SQL/XML? – XMLConcat Cont'd 40

SELECT XMLConcat( XMLElement(name lastname, last_name), XMLElement(name firstname, first_name) )‫‏‬ FROM emp; BlowJoe HeadHelmut

What is SQL/XML? – XMLConcat Cont'd 41

SELECT XMLElement(name main, XMLConcat( XMLElement(name lastname, last_name), XMLElement(name firstname, first_name) ) )‫‏‬ FROM emp; BlowJoe HeadHelmut

What should(n’t) I do with XML? 42

XML

What‫‏‬should(n’t)‫‏‬I‫‏‬do‫‏‬with‫‏‬XML? 43 

Oracle is a RELATIONAL database



Store your data relationally, unless      

Your XML is read only Your XML is transient Your XML is fairly static Your XML is very small You have a discrete key external to the XML Preserved white space is critical

What should I do with XML? 44 

Convert your XML to Relations by Shredding  



Map your relational schema to the XML by its Schema or DTD Use XPath to extract columnar data

Use SQL/XML to recreate the original XML document

What‫‏‬should(n’t)‫‏‬I‫‏‬do‫‏‬with‫‏‬ XML? Cont'd 45



Relational data is much easier to  





Index Update Manipulate

XML data is better for     

Use by some programming languages CMS systems Very unstructured data For reporting Web 2.0 (AJAX, SOAP, Etc)‫‏‬

What‫‏‬should(n’t)‫‏‬I‫‏‬do‫‏‬with‫‏‬ XML? Cont'd 46



XML is great for 

Public stored procedure interfaces 

 



Web based processing  



Publish the XML spec Include a version element or attribute Change parameters and let users adapt over time Many web apps support XML XML + XSLT = Web Happiness

Data interfaces    

Platform independent Current parsers are fast Validation and versioning built-in Public Specifications

SQL/XML for Developers

Lewis Cunningham Data Architect, JP Morgan Chase http://it.toolbox.com/blogs/oracle-guide http://databasewisdom.com/

ODTUG Kaleidoscope 2009 06/21/2009