Database join via calc-element many data-inputs

Introduction
Imagine there are two tables:

• Tb_roof_photos (table1)
  
• Tb_window_photos (table2)

Question
How can you automatically join a roof-photo with a window-photo?
You want to link photos that are from the same housename, location, period, etc.

Create batches
You can make a calc-element like this for table1:

$street = '{table1___street_raw}';
$date = '{table1___date_time}';
$date = date("ymd",strtotime($date));
$house = '{table1___namehouse_raw}';
$vvvv = ($date. $species. $userID .$town1);

return crc32($vvvv);
Than like such you can do for table2 as well in order to generate an equal batch-value.

Compare batches
$db = FabrikWorker::getDbo($loadJoomlaDb = false, $cnnId = 11);
$query = $db->getQuery(true);
$query->select('window_photo')->from('table2')
->where('batch ='. (int)'{table1___batch}');
$db->setQuery($query);
$results = $db->loadResult();

if ($results == "")
{return 'Add a <a href="index.php/windows">Window Photo</a> that matches the location of your roof';}
else {return $results;}

Limiting user-input
UserID, DateTime, and StreetName can be automatically updated by users. Streetname can be retrieved from the field-element and set autocomplete to Geocomplete in combination with the googlemap-element.

Result
If the farmer opens the form a roof photo of the roof can be uploaded and the photo of the window will be automatically added if the autocomplete data that are used to create the batch match with the batch of the other table.