public function getCollection($col)
{
if (mb_orig_strpos($col, '.') === false) {
$col = $this->dbname . '.' . $col;
} else {
$collName = explode('.', $col, 2);
}
if (isset($this->collections[$col])) {
return $this->collections[$col];
}
return $this->collections[$col] = new Collection($col, $this);
}