db_select query advice
Think your query needs to be:

$query = db_select('node', 'development');
$query-&gt;fields('property_type', array('field_property_type_tid'))
  -&gt;condition('development.status', 1, '=')
  -&gt;addJoin('LEFT', 'field_data_belongs2dev', 'property', 'development.nid = property.field_data_belongs2dev_target_id');
$query-&gt;addJoin('LEFT', 'field_data_field_property_type', 'property_type', 'property.field_data_belongs2dev_target_id = property_type.entity_id');
$query-&gt;addExpression('group_concat(property.entity_id)', 'houses_on_development');
$results = $query-&gt;execute();


Hope this should point you in the right direction.