Executing Queries

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Next, we create an XQExpression object, which executes an XQuery expression that is read from a file and returns a sequence of results.

First, here is the XQuery expression, flwor.xq:

for $u in fn:collection('users')/users 
return 
  <user> 
   <name>{ 
     $u/firstname, 
     $u/lastname 
   }</name> 
   {  
    for $h in collection('holdings')/holdings 
    where $h/userid = $u/userid 
    return  
      <stock>{ 
        $h/stockticker, 
        $h/shares 
      }</stock> 
  }</user> 

An XQConnection can create an XQExpression:

XQExpression xqExpression = conn.createExpression(); 
FileReader fileReader = new FileReader("flwor.xq"); 
XQSequence xqSequence = xqExpression.executeQuery(fileReader); 

Now that the query results are in a sequence, you can serialize this sequence using the getSequenceAsString() method. (Serializing is just one way to handle an XQuery result.)

System.out.println(xqSequence.getSequenceAsString()); 

The following result sequence contains a single node, the user element (whitespace has been modified for readability).

<user>  
  <name>  
    <firstname>Jonathan</firstname>  
    <lastname>Robie</lastname>  
  </name>  
  <stock>  
    <stockticker>AMZN</stockticker>  
    <shares>3000</shares>  
  </stock>  
  <stock>  
    <stockticker>EBAY</stockticker>  
    <shares>4000</shares> 
  </stock>  
  <stock>  
    <stockticker>IBM</stockticker>  
    <shares>2500</shares>  
  </stock>  
... 
</user>  

Other similar examples can be found in the XQJExecute example.