XQuery - subsequence Function

Xquery For Dummies: The Videocourse

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XQuery For Beginners: Learn The Basics

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XQuery; Learn The Basics

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The subsequence function is used to get the sequence containing requested items present in a given sequence.

Syntax

subsequence($seq as item()*, $startingLoc as xs:double, $length as xs:double)

Input Parameters

• $seq − provided sequence. Sequence can contain 0 or more items.

• $startingLoc − index of items from which sub-sequence is to be created. Index starts from 1.

• $length − length of subsequence.

Example

XQuery Expression

let $items := (1,2,3,4,5,6)
let $sub-items := subsequence($items,2,4)
return
   <result>   
      
      <items>
      {
         for $item in $sub-items
         return <item>{$item}</item>
      }
      </items>
      
   </result>

Output

<result>
   <items>
      <item>2</item>
      <item>3</item>
      <item>4</item>
      <item>5</item>
   </items>
</result>

Verify the Result

In order to test the above-mentioned functionality, replace the contents of books.xqy (mentioned in Environment Setup chapter) with the above XQuery expression and execute the XQueryTester java program to verify the result.