XQuery

Priscilla Walmsley (pwalmsley@datypic.com)
ISBN: 0596006349
1st edition, 2007, O'Reilly Media, Inc.

Chapter 3: Expressions: XQuery Building Blocks

Example 3-1. Conditional expression

for $prod in (doc("catalog.xml")/catalog/product)
return if ($prod/@dept = 'ACC')
       then <accessoryNum>{data($prod/number)}</accessoryNum>
       else <otherNum>{data($prod/number)}</otherNum>

Example 3-2. Conditional expression returning multiple expressions

for $prod in (doc("catalog.xml")/catalog/product)
return if ($prod/@dept = 'ACC')
       then (<accessoryNum>{data($prod/number)}</accessoryNum>,
            <accessoryName>{data($prod/name)}</accessoryName>)
       else <otherNum>{data($prod/number)}</otherNum>

Example 3-3. Nested conditional expressions

for $prod in (doc("catalog.xml")/catalog/product)
return if ($prod/@dept = 'ACC')
       then <accessory>{data($prod/number)}</accessory>
       else if ($prod/@dept = 'WMN')
            then <womens>{data($prod/number)}</womens>
            else if ($prod/@dept = 'MEN')
                 then <mens>{data($prod/number)}</mens>
                 else <other>{data($prod/number)}</other>

Useful Function. between-inclusive (see also functx:between-inclusive)

declare namespace functx = "http://www.functx.com";
declare function functx:between-inclusive
 ($value as xs:anyAtomicType, $minValue as xs:anyAtomicType,
  $maxValue as xs:anyAtomicType) as xs:boolean  {

   $value >= $minValue and $value <= $maxValue

 };
(: Example call :)
let $prod := doc("catalog.xml")//product[1]
return functx:between-inclusive ($prod/number, 1, 500)