Querying XML - Revision history

Suhridk: /* Queries */

2014-02-15T06:48:23Z

Queries

Suhridk: /* Queries */

2014-02-15T06:42:44Z

Queries

Suhridk: /* Queries */

2014-02-15T06:39:12Z

Queries

Suhridk: /* Queries */

2014-02-15T06:36:38Z

Queries

Suhridk: /* Queries */

2014-02-15T06:32:06Z

Queries

Suhridk: /* XSLT */

2014-02-15T06:15:16Z

XSLT

Suhridk: /* XSLT */

2014-02-12T14:12:58Z

XSLT

Suhridk: /* Xquery examples */

2014-02-12T14:08:37Z

Xquery examples

Suhridk: /* Sample queries */

2014-02-09T05:17:46Z

Sample queries

Suhridk: /* Sample queries */

2014-02-09T05:17:05Z

Sample queries

@@ Line 231: / Line 231: @@
     </table>
     </html>
 </xsl:template>
 </syntaxhighlight>

@@ Line 207: / Line 207: @@
 <xsl:template match="Author">
    <Author LN="{Last_Name}" FN="{First_Name}" />
 </xsl:template>
 </syntaxhighlight>

@@ Line 175: / Line 175: @@
 * Use the above template & add exception templates to make specific changes
-* e.g. ISBN attribute is converted to an ISBN element
+* e.g. ISBN attribute is converted to an ISBN element, Author element is converted to an author attribute
 <syntaxhighlight lang="xml">

@@ Line 162: / Line 162: @@
 * When two templates match, the later template gets priority. However, when one template is more specific than the other, the specific template gets the higher priority.
-* Recursively apply templates :
+* Recursively apply templates : to copy the entire document
 <syntaxhighlight lang="xml">
@@ Line 170: / Line 170: @@
        <xsl:apply-templates select="*|@*|text()" />
     </xsl:copy>
 </xsl:template>
 </syntaxhighlight>

@@ Line 149: / Line 149: @@
 * Copies all books - "." is current element. i.e. retains them in the output XML.
 <syntaxhighlight lang="xml">
 <xsl:template match="Book[@Price &lt; 90]">
     <xsl:copy-of select="." />
 </xsl:template>
 </syntaxhighlight>

← Older revision		Revision as of 06:15, 15 February 2014
Line 128:		Line 128:
	* However, the query paradigm is quite different - based on the notion of transforming the data. Transformation occurs with rules.		* However, the query paradigm is quite different - based on the notion of transforming the data. Transformation occurs with rules.
	* Matching a template and replacing it - Write an expression that find portion of the XML tree based on template matching. Then, replace subtree with what is in the template. The template is specified using XPath.		* Matching a template and replacing it - Write an expression that find portion of the XML tree based on template matching. Then, replace subtree with what is in the template. The template is specified using XPath.
		+	* Templates can be recursively matched
		+	* Extract values, for-each, conditionals
		+
		+	== Queries ==
		+
		+	* Returns only BookTitle & MagazineTitle elements in the output XML.
		+
		+	<syntaxhighlight lang="xml">
		+
		+	<xsl:template match="Book">
		+	<BookTitle> <xsl:value-of select="Title" /> </BookTitle>
		+	</xsl:template>
		+
		+	<xsl:template match="Magazine">
		+	<MagazineTitle> <xsl:value-of select="Title" /> </MagazineTitle>
		+	</xsl:template>
		+
		+
		+	</syntaxhighlight>
		+
		+	* Copies all books - "." is current element. i.e. retains them in the output XML.
		+	<syntaxhighlight lang="xml">
		+
		+	<xsl:template match="Book[@Price < 90]">
		+	<xsl:copy-of select="." />
		+	</xsl:template>
		+
		+	</syntaxhighlight>

@@ Line 127: / Line 127: @@
 * XSLT processor takes the input XML doc and an XSLT specification (which is specified in XML) and transforms the data into an XML document or String. This is similar to DB query processing where we input data & query to the query processor to get the result.
 * However, the query paradigm is quite different - based on the notion of transforming the data. Transformation occurs with rules.
+* Matching a template and replacing it - Write an expression that find portion of the XML tree based on template matching. Then, replace subtree with what is in the template. The template is specified using XPath.

← Older revision		Revision as of 14:08, 12 February 2014
Line 121:		Line 121:

	</syntaxhighlight>		</syntaxhighlight>
		+
		+	= XSLT =
		+
		+	* First XSL (Extensible Stylesheet Language) was introduced and was extended to included Transformations : XSLT.
		+	* XSLT processor takes the input XML doc and an XSLT specification (which is specified in XML) and transforms the data into an XML document or String. This is similar to DB query processing where we input data & query to the query processor to get the result.
		+	* However, the query paradigm is quite different - based on the notion of transforming the data. Transformation occurs with rules.
		+
		+	*

@@ Line 32: / Line 32: @@
 <syntaxhighlight lang="xml">
-* doc("Bookstore.xml")/Bookstore/Book[@Price < 90] - Condition, price < 90 : Will print the whole book
+doc("Bookstore.xml")/Bookstore/Book[@Price < 90] - Condition, price < 90 : Will print the whole book
-* doc("Bookstore.xml")/Bookstore/Book[@Price < 90]/Title - Above, but return only title.
+doc("Bookstore.xml")/Bookstore/Book[@Price < 90]/Title - Above, but return only title.
-* doc("Bookstore.xml")/Bookstore/Book[Remark]/Title - Existence condition, Book must have a remark element
+doc("Bookstore.xml")/Bookstore/Book[Remark]/Title - Existence condition, Book must have a remark element
-* doc("Bookstore.xml")/Bookstore/Book[@Price < 90 and Authors/Author/Last_Name = "Ullman" and Authors/Author/First_Name = "Jennifer" ]/Title  : Bigger condition. The second part is actually  a "there exists". So actually not doing an AND.
+doc("Bookstore.xml")/Bookstore/Book[@Price < 90 and Authors/Author/Last_Name = "Ullman" and Authors/Author/First_Name = "Jennifer" ]/Title  : Bigger condition. The second part is actually  a "there exists". So actually not doing an AND.
-* doc("Bookstore.xml")/Bookstore/Book[@Price < 90 and Authors/Author[Last_Name = "Ullman" and First_Name = "Jennifer" ]/Title : This is the correct one.
+doc("Bookstore.xml")/Bookstore/Book[@Price < 90 and Authors/Author[Last_Name = "Ullman" and First_Name = "Jennifer" ]/Title : This is the correct one.
 </syntaxhighlight>
 <syntaxhighlight lang="xml">
-* doc("Bookstore.xml")//Authors/Author[2] - Return the second author element of each Authors subelement
+doc("Bookstore.xml")//Authors/Author[2] - Return the second author element of each Authors subelement
-* doc("Bookstore.xml")/Book/[contains(Remark, "Great")]/Title : contains function
+doc("Bookstore.xml")/Book/[contains(Remark, "Great")]/Title : contains function
-* doc("Bookstore.xml")//Magazine[Title=doc("Bookstore.xml")//Book/Title] : Self-join. Condition is satisified if there is SOME element that meets it. Implicit existential quantification.
+doc("Bookstore.xml")//Magazine[Title=doc("Bookstore.xml")//Book/Title] : Self-join. Condition is satisified if there is SOME element that meets it. Implicit existential quantification.
-* doc("Bookstore.xml")/Book//*[name(parent::*) != 'Bookstore' and name(parent::*) != 'Book'] : All elements whose parent element is not bookstore or book.  * after parent:: says match any tag of the parent.
+doc("Bookstore.xml")/Book//*[name(parent::*) != 'Bookstore' and name(parent::*) != 'Book'] : All elements whose parent element is not bookstore or book.  * after parent:: says match any tag of the parent.
-* doc("Bookstore.xml")/Bookstore/(Book | Magazine)[Title = following-sibling::*/Title] : All books and magazines that have a non-unique title.  Similarly, preceding-sibling.
+doc("Bookstore.xml")/Bookstore/(Book | Magazine)[Title = following-sibling::*/Title] : All books and magazines that have a non-unique title.  Similarly, preceding-sibling.
-* doc("Bookstore.xml")/Bookstore/(Book | Magazine)[Title = following-sibling::Book/Title] : Instead of star in the axes, we specify an element.
+doc("Bookstore.xml")/Bookstore/(Book | Magazine)[Title = following-sibling::Book/Title] : Instead of star in the axes, we specify an element.
-* doc("Bookstore.xml")//Book[count(Authors/Author[contains(First_Name, 'J')]) = count(Authors/Author/First_Name)] - Universal quantification (for all). Every author's first_name equals J.
+doc("Bookstore.xml")//Book[count(Authors/Author[contains(First_Name, 'J')]) = count(Authors/Author/First_Name)] - Universal quantification (for all). Every author's first_name equals J.
 </syntaxhighlight>
 = XQuery =

@@ Line 23: / Line 23: @@
 <syntaxhighlight lang="xml">
-* doc("Bookstore.xml")/Bookstore/Book/Title - returns titles of all books
+doc("Bookstore.xml")/Bookstore/Book/Title - returns titles of all books
-* doc("Bookstore.xml")/Bookstore/(Book | Magazine)/Title - titles of all books or magazines
+doc("Bookstore.xml")/Bookstore/(Book | Magazine)/Title - titles of all books or magazines
-* doc("Bookstore.xml")/Bookstore/*/Title - wildcard
+doc("Bookstore.xml")/Bookstore/*/Title - wildcard
-* doc("Bookstore.xml")//Title - any Title element anywhere in the tree - Double slash
+doc("Bookstore.xml")//Title - any Title element anywhere in the tree - Double slash
-* doc("Bookstore.xml")//* - Will print the whole tree for the root, then subtree for the child etc
+doc("Bookstore.xml")//* - Will print the whole tree for the root, then subtree for the child etc
-* doc("Bookstore.xml")/Bookstore/Book/data(@ISBN) - Data operator needs to be specified
+doc("Bookstore.xml")/Bookstore/Book/data(@ISBN) - Data operator needs to be specified
 </syntaxhighlight>