Cannot load admin form because of incorrect query

Inside the webform_purge.module file, there are these lines of code:

• Line 35: $query = db_query('SELECT * FROM {webform_submissions} WHERE webform_submissions.submitted < :purge_timestamp', array(':purge_timestamp' => $purge_timestamp));
• Line 200: $query = db_query('SELECT nid FROM {webform_submissions} WHERE webform_submissions.nid = :nid', array(':nid' => $webform->nid));
• Line 204: $query = db_query('SELECT MIN(webform_submissions.submitted) as oldest_date FROM {webform_submissions} WHERE webform_submissions.nid = :nid', array(':nid' => $webform->nid));

When I install the module and go to the admin page (admin/config/webform_purge/manage), I get the following error:

PDOException: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'webform_submissions.nid' in 'where clause': SELECT nid FROM {webform_submissions} WHERE webform_submissions.nid = :nid; Array ( [:nid] => 52465 ) in webform_purge_admin_settings_form() (regel 200 van /var/www/html/sites/all/modules/contrib/webform_purge/webform_purge.module)

Basically, you don't need to specify the name of the table in the WHERE-clause, because you already specified it in the FROM. When I remove those tablenames, you'll end up with the following code:

• Line 35: $query = db_query('SELECT * FROM {webform_submissions} WHERE submitted < :purge_timestamp', array(':purge_timestamp' => $purge_timestamp));
• Line 200: $query = db_query('SELECT nid FROM {webform_submissions} WHERE nid = :nid', array(':nid' => $webform->nid));
• Line 204: $query = db_query('SELECT MIN(submitted) as oldest_date FROM {webform_submissions} WHERE nid = :nid', array(':nid' => $webform->nid));

Now, when I reload the admin form (admin/config/webform_purge/manage), the form will output correctly and no error is being showed.

I created a patch which can hopefully be applied to the dev version of this module, which I added as an attachment.