webform: mysql to postgres

i'm running postgres for the db and want to use the webform module.

unfortunately it seems to be using some mysql specific calls, ie:

$result = db_query("SHOW FIELDS FROM {webform}");

can anyone help me to get this compatible with postgres?

if put the whole function below for reference:

/**
 * _webform_database_lazy_update - Lazy field adder for extra email fields
 * The lazy update function adds any columns in the database that are not
 * listed in its internal magic array.
 * It was purpose constructed to add fields 'email_from' and 'email_subject' as part of the
 * enhanced email patch.
 * The function does not add or delete any data and the upgraded database is backwardly
 * compatible with previous versions of webform.module
 */
function _webform_database_lazy_update() {

        $lazy_update_output = '';
        $field_list = '';
  $table_altered = false;

  // {webform}
        $required_fields = array('nid' => false,'confirmation' => false,'email' => false,'email_from' => false,'email_subject' => false);
  $result = db_query("SHOW FIELDS FROM {webform}");

        // Mark fields that exist in table as true
        while ($record = db_fetch_object($result)){
                $required_fields[$record->Field] = true;
        }

        foreach($required_fields as $field_name => $required_field){
                if(!$required_field){
                        // Field does not exist so we need to create it.
                        switch($field_name){
                                case 'email_subject':           // Contains the component name of the source field for the email subject
                                case 'email_from':                      // Contains the component name of the source field for the email from address.
                                        db_query("ALTER TABLE {webform} ADD COLUMN %s varchar(255)",$field_name);
                                        $table_altered = true;
          $field_list .= " $field_name ";
                                        break;
                                default:
                        }
                }
        }

        if($table_altered){
          $lazy_update_output = 'Database {webform} updated. Fields added: ' . $field_list;
          watchdog('webform',$lazy_update_output, WATCHDOG_NOTICE);
        }

        return $lazy_update_output;
}