Using SQL Queries to Using SQL Queries to Generate XML-Generate XML-

Formatted Data Formatted Data Joline MorrisonJoline Morrison

Mike MorrisonMike Morrison

Department of Computer ScienceDepartment of Computer Science

University of Wisconsin-Eau ClaireUniversity of Wisconsin-Eau Claire

OutlineOutline

Study motivationsStudy motivations Overview of XMLOverview of XML XML SQL query syntaxXML SQL query syntax

OracleOracle SQL ServerSQL Server

ConclusionsConclusions Platform strengths/weaknessesPlatform strengths/weaknesses Suggestions for student activitiesSuggestions for student activities

Study MotivationsStudy Motivations

XML has become the de facto standard XML has become the de facto standard for sharing data acfor sharing data across diverse ross diverse applications and hardware/software applications and hardware/software platformsplatforms

SQL-2003 ISO specifies standards for SQL-2003 ISO specifies standards for forming queries that retrieve XML-forming queries that retrieve XML-formatted data formatted data

But most organizational data is stored in But most organizational data is stored in relational databases...relational databases...

XML OverviewXML Overview

Defines Defines structured datastructured data using using markup markup languagelanguage notation notation

Structured data: Data defined in a specific Structured data: Data defined in a specific and unambiguous formatand unambiguous format

Markup language:Markup language: Uses tags or other symbols to specify document Uses tags or other symbols to specify document

formattingformatting Tags are defined in a document type definition Tags are defined in a document type definition

(DTD)(DTD)

XML FeaturesXML Features

XML DTD allows developers to define XML DTD allows developers to define custom tags to define the syntax, custom tags to define the syntax, semantics, and structure of datasemantics, and structure of data

XML documents are XML documents are text filestext files Can be shared across different applications Can be shared across different applications

and hardware/software platformsand hardware/software platforms

Example XML DocumentExample XML Document<?xml version="1.0" encoding="UTF-8" ?><books> <book isbn="99999-99999"> <title>CS 365: A Visual History</title> <authors> <author id="100">

<firstname>Tom</firstname><lastname>Moore</lastname>

</author> <author id="101">

<firstname>Leonard</firstname><lastname>Larsen</lastname>

</author> </authors> <publisher>UWEC-CS Press</publisher> <publishyear>2000</publishyear> <price type="USD">10.00</price> </book>

Attribute value

Element value

Aggregated dataelement

Prolog

Representing Data Relationships Representing Data Relationships in XML Documentsin XML Documents

Relationships limited to 1:MRelationships limited to 1:M Relationships must be hierarchicalRelationships must be hierarchical

<book isbn="99999-99999"> <title>CS 365: A Visual History</title> <authors> <author id="100">

<firstname>Tom</firstname><lastname>Moore</lastname>

</author> <author id="101">

<firstname>Leonard</firstname><lastname>Larsen</lastname>

</author> </authors>

OutlineOutline

Research motivationsResearch motivations Overview of XMLOverview of XML XML SQL query syntaxXML SQL query syntax

OracleOracle SQL ServerSQL Server

ConclusionsConclusions Platform strengths/weaknessesPlatform strengths/weaknesses Suggestions for student activitiesSuggestions for student activities

XML SQL QueriesXML SQL Queries

Approach: create SQL queries that Approach: create SQL queries that retrieve relational database data and retrieve relational database data and "wrap" it in predefined XML tags "wrap" it in predefined XML tags

ISO-2003 SQL standards specify required ISO-2003 SQL standards specify required functionality but don't prescribe syntaxfunctionality but don't prescribe syntax Different vendors implement the same Different vendors implement the same

functionality quite differently!functionality quite differently!

Example XML SQL Queries Example XML SQL Queries

Operations: Operations: Format values as elements & attributesFormat values as elements & attributes Create aggregate elements to represent Create aggregate elements to represent

relationshipsrelationships

Platforms: Oracle & SQL ServerPlatforms: Oracle & SQL Server

Oracle:Oracle:Formatting Data as ElementsFormatting Data as Elements

SELECT XMLElement("department", department_name)FROM university_department ORDER BY department_name;

<department>Accounting</department><department>Chemistry</department><department>Computer Science</department>…

XMLElementXMLElement function creates a new XML function creates a new XML elementelement

Parameters specify element names and Parameters specify element names and associated data valuesassociated data values

Oracle:Oracle:Formatting Data as AttributesFormatting Data as Attributes

SELECT XMLElement("department", XMLAttributes(department_id AS "id", department_name AS "name"))FROM university_department ORDER BY department_name;

<department id="2" name="Accounting"></department><department id="5" name="Chemistry"></department><department id="4" name="Computer Science"></department>

You first use You first use XMLElementXMLElement to create the to create the elementelement XMLAttributesXMLAttributes function retrieves and formats function retrieves and formats

one or more data values as attributesone or more data values as attributes

Oracle:Oracle:Creating Aggregate DataCreating Aggregate Data

SELECT XMLElement("department", XMLAgg(XMLElement("course", course_name)))FROM university_department a INNER JOIN university_course bON a.department_id = b.department_idGROUP BY department_name;

<department> <course>ACCT 201</course> <course>ACCT 312</course></department><department><course>CHEM 205</course></department><department><course>CS 245</course></department>

Create the parent element using Create the parent element using XMLElementXMLElement Retrieve the child values as elements using the Retrieve the child values as elements using the

XMLAggXMLAgg functionfunction

Oracle:Oracle:Nesting XML FunctionsNesting XML Functions

SELECT XMLElement("department", XMLAttributes(department_name AS "name"), XMLElement("courses", (XMLAgg(XMLElement("course", course_name)))))FROM university_department a INNER JOIN university_course bON a.department_id = b.department_idWHERE a.department_id = 1GROUP BY department_name;<department name="Management Information Systems"> <courses> <course>MIS 240</course> <course>MIS 310</course> <course>MIS 344</course></courses></department>

Oracle allows you to nest XML functions to Oracle allows you to nest XML functions to retrieve data in a variety of formats...retrieve data in a variety of formats...

SQL Server:SQL Server:General ApproachGeneral Approach

SELECT ...FOR XML Mode[, ELEMENTS]

ModeMode values: values: RAWRAW: returns each record as an XML element enclosed in a : returns each record as an XML element enclosed in a

<row> element<row> element AUTOAUTO: returns each record as a named XML element and : returns each record as a named XML element and

hierarchically nests child nodes from JOIN querieshierarchically nests child nodes from JOIN queries EXPLICITEXPLICIT: provides precise control on how data values are : provides precise control on how data values are

formattedformatted ELEMENTS option: formats each field as a separate ELEMENTS option: formats each field as a separate

elementelement

SQL Server:SQL Server:Formatting Data as ElementsFormatting Data as Elements

SELECT DepartmentName, CourseNameFROM UniversityDepartment a INNER JOIN UniversityCourse bON a.DepartmentID = b.DepartmentIDORDER BY DepartmentName, CourseNameFOR XML RAW

<row DepartmentName="Accounting" CourseName="ACCT 201" /><row DepartmentName="Accounting" CourseName="ACCT 312" /><row DepartmentName="Chemistry" CourseName="CHEM 205" />

RAWRAW modemode::

SQL Server:SQL Server:Formatting Data as ElementsFormatting Data as Elements

SELECT DepartmentName, CourseNameFROM UniversityDepartment a INNER JOIN UniversityCourse bON a.DepartmentID = b.DepartmentIDORDER BY DepartmentName, CourseNameFOR XML RAW, ELEMENTS

<row> <DepartmentName>Accounting</DepartmentName> <CourseName>ACCT 201</CourseName></row><row> <DepartmentName>Accounting</DepartmentName> <CourseName>ACCT 312</CourseName></row>

RAW, ELEMENTSRAW, ELEMENTS option: option:

SQL Server:SQL Server:Formatting Data as ElementsFormatting Data as Elements

SELECT DepartmentName, CourseNameFROM UniversityDepartment dept INNER JOIN UniversityCourse courseON dept.DepartmentID = course.DepartmentIDORDER BY DepartmentName, CourseNameFOR XML AUTO, ELEMENTS

<dept> <DepartmentName>Accounting</DepartmentName> <course> <CourseName>ACCT 201</CourseName> </course> <course> <CourseName>ACCT 312</CourseName> </course></dept><dept>

AUTO, ELEMENTSAUTO, ELEMENTS option: option:

SQL Server:SQL Server:Formatting Data as AttributesFormatting Data as Attributes

SELECT DepartmentName, CourseNameFROM UniversityDepartment dept INNER JOIN UniversityCourse courseON dept.DepartmentID = course.DepartmentIDORDER BY DepartmentName, CourseNameFOR XML AUTO

<dept DepartmentName="Accounting"> <course CourseName="ACCT 201" /> <course CourseName="ACCT 312" /></dept><dept DepartmentName="Chemistry"> <course CourseName="CHEM 205" /></dept><dept DepartmentName="Computer Science"> <course CourseName="CS 245" /></dept>

AUTO mode (remove ELEMENTS option)AUTO mode (remove ELEMENTS option)::

SQL Server:SQL Server:XML EXPLICIT modeXML EXPLICIT mode

Allows you to specify parent and child Allows you to specify parent and child elements precisely elements precisely

Each level is defined within a separate queryEach level is defined within a separate query Queries are joined using the UNION operator Queries are joined using the UNION operator

Level 1 query:Level 1 query: SELECT 1 as tag, NULL as parent, DepartmentName AS [dept!1!name!element]FROM UniversityDepartmentORDER BY DepartmentNameFOR XML EXPLICIT<dept> <name>Accounting</name></dept><dept> <name>Chemistry</name></dept>

XML EXPLICIT query with 2 levelsXML EXPLICIT query with 2 levelsSELECT 1 As tag, NULL As parent, DepartmentName As [dept!1!dname], NULL As [course!2!cname!element], NULL As [course!2!title!element]FROM UniversityDepartmentUNIONSELECT 2 As tag, 1 As parent, DepartmentName,CourseName, CourseTitleFROM UniversityDepartment a INNER JOIN UniversityCourse bON a.DepartmentID = b.DepartmentIDORDER BY [dept!1!dname], [course!2!cname!element]FOR XML EXPLICIT<dept dname="Accounting"> <course> <cname>ACCT 201</cname><title>Accounting I</title> </course> <course> <cname>ACCT 312</cname> <title>Managerial Accounting</title> </course></dept>

OutlineOutline

Study motivationsStudy motivations Overview of XMLOverview of XML XML SQL query syntaxXML SQL query syntax

OracleOracle SQL ServerSQL Server

ConclusionsConclusions Platform strengths/weaknessesPlatform strengths/weaknesses Suggestions for student activitiesSuggestions for student activities

ConclusionsConclusions

Platform strengths/weaknessesPlatform strengths/weaknesses Oracle syntax seems a little shorter and Oracle syntax seems a little shorter and

cleaner overallcleaner overall SQL Server automatically creates SQL Server automatically creates

aggregate data from JOIN queriesaggregate data from JOIN queries SQL Server EXPLICIT mode provides SQL Server EXPLICIT mode provides

precise formatting precise formatting At a high cost!At a high cost!

ConclusionsConclusions

Platform strengths/weaknesses Platform strengths/weaknesses (continued)(continued) Oracle allows you to create aggregated Oracle allows you to create aggregated

data in a way that SQL Server does not:data in a way that SQL Server does not:

<department name="Management Information Systems"> <courses> <course>MIS 240</course> <course>MIS 310</course> <course>MIS 344</course></courses></department>

ConclusionsConclusions

Suggestions for student activitiesSuggestions for student activities Manually create XML-formatted data for a series Manually create XML-formatted data for a series

of related database tablesof related database tables Create queries in both Oracle and SQL Server to Create queries in both Oracle and SQL Server to

retrieve XML-formatted data and analyze syntax retrieve XML-formatted data and analyze syntax differencesdifferences

Generate XML-formatted data and display it in a Generate XML-formatted data and display it in a browserbrowser

Generate XML-formatted data and transform it Generate XML-formatted data and transform it into and HTML document using XSLTsinto and HTML document using XSLTs

Additional ResourcesAdditional Resources

Scripts to create databases in Oracle & Scripts to create databases in Oracle & SQL ServerSQL Server

Electronic copy of the paperElectronic copy of the paper Electronic copy of the slideshowElectronic copy of the slideshow

http://www.cs.uwec.edu/~morrisjp/Public/Conferences/MICS