import groovy.sql.Sql
import groovy.xml.MarkupBuilder
def schema = "PROD"
def sql = Sql.newInstance("jdbc:oracle:thin:@hostname:1526:${schema}", "scott", "tiger", "oracle.jdbc.driver.OracleDriver")

/* Request */
def req = """
SELECT id,  name, givenname, unit FROM ${schema}.people
WHERE
in_unit=1
AND visible=0
"""
def out = new File('out.xml')
def writer = new FileWriter( out )
def xml = new MarkupBuilder( writer )

xml.agents {
    sql.eachRow( req as String  ) {
        /* For each row output detail */
        row ->
            xml.agent(id:row.id) {
                name( row.name )
                givenname( row.givenname )
                unit( row.unit )
                }
    }
}

<agents>                               <!-- xml.agents {                  -->
  <agent id='870872'>                  <!--    agent(id:row.id) {         -->
    <name>ABTI</name>                  <!--       name( row.nom )         -->
    <givenname>Jean</givenname>        <!--       givenname( row.prenom ) -->
    <unit>Sales</unit>                 <!--       unit( row.unite )       -->
  </agent>                             <!--    }                          -->
...
</agents>