public function getColumns ($db, $table)
	{
		
		// Get columns
		
		if (!isset ($this->columns[$db][$table]))
		{
			$this->columns[$db][$table]	= $this->db->query ('SHOW COLUMNS FROM ' . $db . '.' . $table)->fetchAll (\PDO::FETCH_NUM);
		}
		
		// Return columns
		
		return $this->columns[$db][$table];
		
	}