public function write_start($table_prefix)
{
if (!$this->is_initialized) {
throw new extractor_not_initialized_exception();
}
$sql_data = "--\n";
$sql_data .= "-- phpBB Backup Script\n";
$sql_data .= "-- Dump of tables for {$table_prefix}\n";
$sql_data .= "-- DATE : " . gmdate("d-m-Y H:i:s", $this->time) . " GMT\n";
$sql_data .= "--\n";
$sql_data .= "BEGIN TRANSACTION\n";
$sql_data .= "GO\n";
$this->flush($sql_data);
}