1. XML DOCUMENTS & DATABASES

2. Summary of Introduction to XML
HTML vs. XML
Types of Data
Basics of XML
XML Syntax, XML Elements, XML Attributes
XML Document Type Definition
- Types, Elements, Attributes, Example
XML Schema
- XSD vs. DTD, Simple elements, Complex elements, Attributes, Facets, Indicators

3. XML & Databases Extracting XML Documents from Relational Databases
XML Querying:
XPath
XQuery

4. Extracting XML Documents

5. Extracting XML Documents

6. Extracting XML Documents

7. Extracting XML Documents

8. Extracting XML Documents

9. Extracting XML Documents

10. Extracting XML Documents

11. XML QUERYING
XML PATH LANGUAGE
- XPath
XML QUERY LANGUAGE
- XQuery

12. XML PATH LANGUAGE - XPATH
XPath is a language for addressing parts of an XML Document.
XPath uses paths to define XML elements
XPath defines a library of standard functions
XPath is not written using XML Syntax
XPath is a W3C Standard !!
XPath provides common syntax and semantics for XSLT and XPointer

13. XPath – XML Data model root nodes element nodes text nodes
attribute nodes
namespace nodes
processing instruction nodes
comment nodes

14. XPath Basics - Path In general -> sandeep/xml/xmlpath.ppt
In XPath -> /catalog/cd/price

15. XPath Syntax with examples (overview)
Locating nodes:
/catalog/cd/price (absolute path), //cd
Unknown elements: Use wildcard (*)
/catalog/*, /*/*/price , // *
Several paths: //title | // artist
Selecting attributes: Use prefix
, = ‘UK’] ,
Specifying Predicates:
/catalog/cd[1] , //cd[price], //cd[price = 10]/price

16. XPath – Location Path
Most important grammatical construct in the XPath language, that results in a node-set.
EBNF format:
Location ::= RelativeLocationPath
| AbsoluteLocationPath
AbsoluteLocationPath: /step/step/...
RelativeLocationPath: step/step/...

17. XPath – Location Path EBNF format: Location ::= RelativeLocationPath |
AbsoluteLocationPath
AbsoluteLocationPath::=‘/’RelativeLocationPath?
| AbbreviatedAbsoluteLocationPath
RelativeLocationPath::=Step|RelativeLocationPath ‘/’ Step | AbbreviatedRelativeLocationPath

18. XPath – Location Path Location Step has three parts:
An Axis – Tree Relationship
A Node Test – Node type, expanded-name
Zero or more Predicates – Expressions to refine set of nodes.
Syntax: axisname :: nodetest [predicate]
Example: child :: price [price = 10]
Context: context node, context position, context size, variable bindings, function library, namespace declarations

19. XPath – Location Path – Uabbreviated Axis Names

20. XPath – Location Path - Examples
child::cd , child::*, child::text()
attribute::name,attribute::*
descentant::catalog, descendant-or-self::cd
child::catalog/self::cd, child::cd[position() = last()]
/descendant::cd, /descendant::catalog/child::cd
child::para[position()=5][attribute::type=“warning”]………what if .. [att..][pos..]
child::*[self::cd or self::catalog]

21. XPath – Predicates A Predicate filters a node-set to a new node-set.
The condition is placed in [ ]

22. XPath – Abbreviated Syntax
Examples:
cd, cd[1], cd[last()],
*/cd, //cd, .., .,
.//cd

23. XPath - Expressions Types:
Numerical -> ,- ,* ,div , mod
Equality -> =, !=
Relational -> <,>,<=,>=
Boolean -> or, and
XPath – Functions
Node – set functions, Numeric fuctions,
String functions, Boolean functions

24. XPath – Core Function Library
Node – Set:
count() ; setnumber=count(node-set)
id() ; node-set=id(value)
last() ; listnumber=last()
local-name() ; namestring=local-name(node)
name() ; nodestring=name(node)
namespace-uri() ; nodeuri=namespace-uri(node)
position() ; processednumber=position()
Boolean:
boolean() ; bool = boolean(value)
false() ; number(false())
lang() ; bool = lang(language)
not() ; not(false())
true() ; number(true())

25. XPath – Core Function Library – String
concat() ; string=concat(val1, val2, ..)
contains() ; bool=contains(val,substr)
normalize-space() ; string=normalize-space(string)
starts-with() ; bool=starts-with(string,substr)
string() ; string(value)
string-length() ; number=string-length(string)
substring() ; string=substring(string,start,length)
substring-after() ; string=substring-after(string,substr)
substring-before() ; string=
substring-before(string,substr)
translate() ; string=translate(value,string1,string2)

26. XML QUERY LANGUAGE
XML Query Language is used to extract data by querying the XML Documents
XML is built on XPath which is used in writing queries
XML Query and XML Path have same Data Model, Function Library, Data types, Operators
XML Query is not yet a W3C Standard !

27. XML Query Language – Extracting Nodes
Using Functions
doc(example.xml)
Using Functions and Paths
doc(example.xml)/catalog/cd or doc(..)//cd
Using Expressions
doc(example.xml)/catalog/cd[price < 10]

28. XML Query – FLOWR Expression
For <variable bindings to individual nodes>
Let <variable bindings to a collection of nodes>
Order by <query specifications>
Where <conditions>
Return <query result specifications>

29. XML QUERY - Example

30. ANY “QUERIES”? Hint: use xml

31. REFERENCES
Fundamentals of Database Systems, Fourth Edition, Elmasir and Navathe