XQuery

Easing into XQuery

The rest of this chapter takes you through a set of example queries, each of which builds on the previous one. Three XML documents are used repeatedly as input documents to the query examples throughout the book. They will be used so frequently that it may be worth printing them from the companion web site so that you can view them alongside the examples.

These three examples are quite simplistic, but they are useful for educational purposes because they are easy to learn and remember while looking at query examples. In reality, most XQuery queries will be executed against much more complex documents, and often against multiple documents as a group. However, in order to keep the examples reasonably concise and clear, this book will work with smaller documents that have a representative mix of XML characteristics.

The catalog.xml document is a product catalog containing general information about products (Example 1-1).

Example 1-1. Product catalog input document (catalog.xml)

<catalog>
  <product dept="WMN">
    <number>557</number>
    <name language="en">Fleece Pullover</name>
    <colorChoices>navy black</colorChoices>
  </product>
  <product dept="ACC">
    <number>563</number>
    <name language="en">Floppy Sun Hat</name>
  </product>
  <product dept="ACC">
    <number>443</number>
    <name language="en">Deluxe Travel Bag</name>
  </product>
  <product dept="MEN">
    <number>784</number>
    <name language="en">Cotton Dress Shirt</name>
    <colorChoices>white gray</colorChoices>
    <desc>Our <i>favorite</i> shirt!</desc>
  </product>
</catalog>

The prices.xml document contains prices for the products, based on effective dates (Example 1-2).

Example 1-2. Price information input document (prices.xml)

<prices>
  <priceList effDate="2006-11-15">
    <prod num="557">
      <price currency="USD">29.99</price>
      <discount type="CLR">10.00</discount>
    </prod>
    <prod num="563">
      <price currency="USD">69.99</price>
    </prod>
    <prod num="443">
      <price currency="USD">39.99</price>
      <discount type="CLR">3.99</discount>
    </prod>
  </priceList>
</prices>

The order.xml document is a simple order containing a list of products ordered (referenced by a number that matches the number used in catalog.xml), along with quantities and colors (Example 1-3).

Example 1-3. Order input document (order.xml)

<order num="00299432" date="2006-09-15" cust="0221A">
  <item dept="WMN" num="557" quantity="1" color="navy"/>
  <item dept="ACC" num="563" quantity="1"/>
  <item dept="ACC" num="443" quantity="2"/>
  <item dept="MEN" num="784" quantity="1" color="white"/>
  <item dept="MEN" num="784" quantity="1" color="gray"/>
  <item dept="WMN" num="557" quantity="1" color="black"/>
</order>