Metadata Based Queries

You can query for documents based on the metadata that you set for them. To do so, do the following:

Define a namespace for the query that uses the URI that you set for the metadata against which you will perform the query. If you did not specify a namespace for your metadata when you added it to the document, use an empty string.
Perform the query using the special dbxml:metadata() from within a predicate.

For example, suppose you placed a timestamp in your metadata using the URI 'http://dbxmlExamples/timestamp' and the attribute name 'timeStamp'. Then you can query for documents that use a specific timestamp as follows:

CopyC#

//get our manager
using (var mgr = new XmlManager(ManagerInitOptions.AllowExternalAccess | ManagerInitOptions.AllowAutoOpen))
{
    //open a container
    using (var container = mgr.OpenContainer(baseUri + testdb))
    {
        Console.WriteLine("container has {0} documents.", container.GetNumDocuments());
        // add a container alias if your container is not in 
        // the same directory as your application
        container.AddAlias("testdb");
        // get a query context
        QueryContext queryContext = mgr.CreateQueryContext();
        // Declare a namespace. The first argument, 'ts', is the
        // namespace prefix and in this case it can be anything so
        // long as it is not reused with another URI within the same
        // query.
        queryContext.SetNamespace("ts","http://dbxmlExamples/timestamp");
        // the query - note the use of the 'timeStamp' 
        // metadata variable name
        string xquery = "collection('testdb')/*[dbxml:metadata('ts:timeStamp')='00:12:01']";
        // prepare the query
        XQueryExpression expression = mgr.Prepare(xquery, queryContext);
        // execute the query
        XmlResults results = expression.Execute(queryContext);
        container.Close();
    }
}

Queries are case-sensitive.