Getting Started with DB2 Express-C

278 Getting Started with DB2 Express-C
Example 5
The example illustrated in Listing 15.12 demonstrates again the XMLQUERY function
which takes an XQuery FLWOR expression; however, note that this time we are returning
not only XML, but also HTML.
SELECT xmlquery('for $e in $c/Client/email[1]/text()
return {$e}'
passing contact as "c")
FROM clients
WHERE status = 'Gold'
Listing 15.12 - An example returning XML and HTML
The return clause of XQuery enables you to transform XML output as needed. Using the
text()function in the first line indicates that only the text representation of the first email
address of qualifying customers is of interest. The second line specifies that this
information is to be surrounded by HTML paragraph tags.
Example 6
The following example uses the XMLELEMENT function to create a series of item
elements, each of which contain sub-elements for the ID, brand name, and stock keeping
unit (SKU) values obtained from corresponding columns in the items table. Basically, you
can use the XMLELEMENT function when you want to convert relational data to XML data.
This is illustrated in Listing 15.13.
SELECT
xmlelement (name "item", itemname),
xmlelement (name "id", id),
xmlelement (name "brand", brandname),
xmlelement (name "sku", sku)
FROM items
WHERE srp < 100
Listing 15.13 - An example using XMLELEMENT
The query in Listing 15.13 would return the output as shown in Listing 15.14
4272
Classy
981140
…
1193
Natural