submitted to: ms. poonam saini, asst. prof., nitttr submitted by: rohit handa 111430 me (modular)...
TRANSCRIPT
Submitted To:Ms. Poonam Saini,Asst. Prof., NITTTR
Submitted By:Rohit Handa111430ME (Modular) CSE2011 Batch
• A "Well Formed" XML document has correct XML syntax.
• No syntax, spelling, punctuation, grammar errors, etc. in its markup. These kinds of errors can cause XML document difficult to parse.
• An XML Parser is software that reads XML documents and interprets the code according to the XML standard. A parser is needed to perform actions on XML.
XML Syntax– XML documents must have a root element
<root> <child> <subchild>.....</subchild> </child> </root>
– XML elements must have a closing tag<p>This is a paragraph.</p>
– XML tags are case sensitive<Message>This is incorrect</message> <message>This is correct</message>
– XML elements must be properly nested<b><i>This text is bold and italic</i></b>
– XML attribute values must be quoted<note date="12/11/2007"> <to>Tove</to> <from>Jani</from> </note>
Valid XML• An XML document is valid, if the element structure and
markup of the XML document matches a defined standard of relationships, in addition to having well formed markup.
• One standard used to validate XML is a DTD, or Document Type Declaration,
<?xml version="1.0" encoding="ISO-8859-1"?><!DOCTYPE note SYSTEM "Note.dtd"> <note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading>
<body>Don't forget me this weekend!</body> </note>
DTD (Document Type Definition)• The purpose of a DTD is to define the structure of an XML document. • The purpose of a DTD is to define the legal building blocks of an XML
document.• A DTD defines the document structure with a list of legal elements and
attributes.
<!DOCTYPE note [ <!ELEMENT note (to, from, heading, body)> <!ELEMENT to (#PCDATA)> <!ELEMENT from (#PCDATA)> <!ELEMENT heading (#PCDATA)> <!ELEMENT body (#PCDATA)> ]>
Rules for Creating DTDs • When creating a DTD, all the elements and attributes
need to be defined to be used in the XML documents.
• Some syntax to remember when creating DTDs are:
DTD (Contd.)
• Elements are declared in the following manner: <!ELEMENT elementName ( elementParts ) >
• Attributes are declared like this: <!ATTLIST elementName attributeName attributeType attributeDefault >
Internal DTD• If the DTD is declared inside the XML file, it should be
wrapped in a DOCTYPE definition with the following syntax:
<!DOCTYPE root-element [element-declarations]>
<?xml version="1.0"?> <!DOCTYPE note [ <!ELEMENT note (to,from,heading,body)> <!ELEMENT to (#PCDATA)> <!ELEMENT from (#PCDATA)> <!ELEMENT heading (#PCDATA)> <!ELEMENT body (#PCDATA)> ]>
<note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me this weekend</body> </note>
!DOCTYPE note defines that the root element of this document
is note
!ELEMENT note defines that the note element contains 4 elements “to, from, heading,
body”
PCDATA means parsed character data.
The text will be examined by the parser for entities and
markup.
External DTD• If the DTD is declared in an external file, it should be wrapped in a DOCTYPE
definition with the following syntax:
<!DOCTYPE root-element SYSTEM "filename"> • <?xml version="1.0"?>
<!DOCTYPE note SYSTEM "note.dtd"><note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body></note>
And this is the file "note.dtd" which contains the DTD:• <!ELEMENT note (to,from,heading,body)>
<!ELEMENT to (#PCDATA)><!ELEMENT from (#PCDATA)><!ELEMENT heading (#PCDATA)><!ELEMENT body (#PCDATA)>
XPATH
• XPath is a syntax for defining parts of an XML document
• XPath uses path expressions to navigate in XML documents
• XPath is a W3C recommendation
XML Nodes• XML
documents are treated as trees of nodes. The topmost element of the tree is called the root element.
Bookstore
Title Author
Giada De Laurentiis
Year
2005
Price
30.00
Book[2] Book[n]…….
… …
Book[1]
EverydayItalian
Select all the titles
• Everyday Italian
• Harry Potter
• XQuery Kick Start
• Learning XML
/bookstore/book/title
Bookstore
Book[2]
Title
Everyday Italian
Title
Harry Potter
Title
XQUERY Quick Start
Title
Learning XML
Book[1] Book[3] Book[4]
… … … …
Select the title of the first book
• Everyday Italian
/bookstore/book[1]/titleBookstore
Book[index]
Title
Everyday Italian
Title
Harry Potter
Title
XQUERY Quick Start
Title
Learning XML
Select all the prices
• 30.00• 29.99• 49.99• 39.95
/bookstore/book/priceBookstore
Book[index]
Price
30.00
Price
29.99
Price
49.99
Price
39.95
Select price nodes with price>35
• 49.99• 39.95
/bookstore/book[price>35]/priceBookstore
Book[index]
Price
30.00
Price
29.99
Price
49.99
Price
39.95
Display books with price>35
• XQuery Kick Start• Learning XML
/bookstore/book[price>35]/titleBookstore
Books
Price
30.00
Price
29.99
Price
49.99
Price
39.95
Display author list with price<30
• J.K. Rowling
/bookstore/book[price<30]/authorBookstore
Book[index]
Price
30.00
Price
29.99
Price
49.99
Price
39.95
XPath Operators• Operator Description Example Return value• | Computes two node-sets //book | //cd Returns a node-set with all book
and cd elements• + Addition 6 + 4 10• - Subtraction 6 - 4 2• * Multiplication 6 * 4 24• div Division 8 div 4 2• = Equal price=9.80 true if price is 9.8
false if price is 9.90• != Not equal price!=9.80 true if price is 9.90
false if price is 9.80• < Less than price<9.80 true if price is 9.00
false if price is 9.80• <= Less than or equal to price<=9.80 true if price is 9.00
false if price is 9.90• > Greater than price>9.80 true if price is 9.90
false if price is 9.80• >= Greater than or equal to price>=9.80 true if price is 9.90
false if price is 9.70• or or price=9.80 or price=9.70 true if price is 9.80
false if price is 9.50• and and price>9.00 and price<9.90 true if price is 9.80
false if price is 8.50• mod Modulus (division remainder) 5 mod 2 1
XML Selection
Selecting Nodes• XPath uses path expressions to select nodes in an XML
document. The node is selected by following a path or steps.
nodename Selects all child nodes of the named node/ Selects from the root node// Selects nodes in the document from the
current node that match the selection no matter where they are
. Selects the current node
.. Selects the parent of the current node
Advantages• XPath expressions can be automatically generated by the
XPath expression builder. • Uses a familiar syntax for expressing locations in an XML
document hierarchy. • Good document node selection capability across multiple
documents. • Contains easily used functions
Disadvantages• Limited set of built in functions. • Lacks programmability. • Restricted to manipulating documents at relatively large
levels of granularity.
XML Query
• XQuery was designed to query XML data.• XQuery is the language for querying XML data• XQuery for XML is like SQL for databases• XQuery is built on XPath expressions• XQuery is supported by all major databases• XQuery is a W3C Recommendation
• The doc() function is used to open the xml file doc("books.xml")
• XQuery uses path expressions to navigate through elements in an XML document.
• XQuery uses predicates to limit the extracted data from XML documents.
XQUERY
How to Select Nodes From "books.xml"?
doc("books.xml")/bookstore/book/title
Select all the book elements under the bookstore element that have a price element with a value that is
less than 30.
doc("books.xml")/bookstore/book[price<30]
How to Select Nodes From "books.xml"?
• The for clause selects all book elements under the bookstore element into a variable called $x.
• The where clause selects only book elements with a price element with a value greater than 30.
• The order by clause defines the sort-order. Will be sort by the title element.
• The return clause specifies what should be returned. Here it returns the title elements.
for $x in doc("books.xml")/bookstore/bookwhere $x/price>30order by $x/titlereturn $x/title
Result of the Query
<title lang="en">Learning XML</title><title lang="en">XQuery Kick Start</title>
SummaryXML & Database
XML view Database viewXML Data
XPath Referring to a field, such asStudent.id
XQuery SQL
PropertiesSemi structured Structured
Exchange & Shairing Storage
Self describing RDBMS enforced constratints
