Chapter 4: Navigating XML by Using Paths

Table 4-1. Simple path expressions

Example	Return value
`doc("catalog.xml")/catalog`	The `catalog` element that is the outermost element of the document
`doc("catalog.xml")//product`	All `product` elements anywhere in the document
`doc("catalog.xml")//product/@dept`	All `dept` attributes of `product` elements in the document
`doc("catalog.xml")/catalog/*`	All child elements of `catalog`
`doc("catalog.xml")/catalog/*/number`	All `number` elements that are grandchildren of `catalog`

Example 4-1. Prefixed name tests

Input document (prod_ns.xml)

<prod:product xmlns:prod="http://datypic.com/prod">
  <prod:number>563</prod:number>
  <prod:name language="en">Floppy Sun Hat</prod:name>
</prod:product>

Query

declare namespace prod = "http://datypic.com/prod";
<prod:prodList>{
  doc("prod_ns.xml")/prod:product/prod:number
}</prod:prodList>

Results

<prod:prodList xmlns:prod="http://datypic.com/prod">
  <prod:number>563</prod:number>
</prod:prodList>

Table 4-4. Unabbreviated and abbreviated syntax examples

Unabbreviated syntax	Abbreviated equivalent
`child::product`	`product`
`child::*`	`*`
`self::node()`	`.`
`attribute::dept`	`@dept`
`attribute::*`	`@*`
`descendant::product`	`.//product`
`child::product/descendant::name`	`product//name`
`parent::node()/number`	`../number`

Table 4-5. More complex steps (examples start with doc("catalog.xml")/catalog/)

Example	Return value
`product/(number \| name)`	All `number` AND `name` children of `product`.
`product/(* except number)`	All children of `product` except `number`. See for more information on the `\|` and `except` operators.
`product/(if (desc) then desc else name)`	For each `product` element, the `desc` child if it exists; otherwise, the `name` child.
`product/substring(name, 1, 30)`	A sequence of `xs:string` values that are substrings of product names.

Table 4-6. Predicates (examples start with doc("catalog.xml")/catalog/)

Example	Return value
`product[name = "Floppy Sun Hat"]`	All `product` elements that have a `name` child whose value is equal to `Floppy Sun Hat`
`product[number < 500]`	All `product` elements that have a `number` child whose value is less than 500
`product[@dept = "ACC"]`	All `product` elements that have a `dept` attribute whose value is `ACC`
`product[desc]`	All `product` elements that have at least one `desc` child
`product[@dept]`	All `product` elements that have a `dept` attribute
`product[@dept]/number`	All `number` children of `product` elements that have a `dept` attribute

Table 4-7. Position in predicates (examples start with doc("catalog.xml")/catalog/)

Example	Return value
`product[2]`	The second `product` child of `catalog`
`product[position() = 2]`	The second `product` child of `catalog`
`product[position() > 1]`	All `product` children of `catalog` after the first one
`product[last()-1]`	The second to last `product` child of `catalog`
`product[last()]`	The last `product` child of `catalog`
`*[2]`	The second child of `catalog`, regardless of name
`product[3]/*[2]`	The second child of the third `product` child of `catalog`