protected function fixTableSource($refTbl)
    {
        $outS = [];
        if (substr($refTbl, 0, 1) !== '`') {
            $outS[] = '`';
        }
        $psT = strpos($refTbl, '.`');
        if ($psT !== false) {
            $refTbl = substr($refTbl, $psT + 2, strlen($refTbl) - $psT);
        }
        $outS[] = $refTbl;
        if (substr($refTbl, -1) !== '`') {
            $outS[] = '`';
        }
        return implode('', $outS);
    }