startTransaction() public method

public startTransaction ( )
$database->throw_exception_on_error = true;
$database->error_handler = false;
$zipArchiveLocation = $fileName;
$zipContentsQueryable = getZipContentsAsQueryable($zipArchiveLocation);
$csvEntry = $zipContentsQueryable->where(function ($v) {
    return endsWith($v["name"], "csv");
})->single();
$csvData = getZipContentOfFile($zipArchiveLocation, $csvEntry['name']);
while (ord($csvData[0]) > 127) {
    $csvData = substr($csvData, 1);
}
$csvParser = new parseCSV();
$csvParser->delimiter = ";";
$csvContentsQueryable = from($csvParser->parse_string(utf8_decode($csvData)));
try {
    $database->startTransaction();
    $existingRecordsQueryable = from($database->query("SELECT * FROM dealer"));
    $oldRecords = $existingRecordsQueryable->where('$v["IsDeleted"] == 0')->where(function ($row) use($csvContentsQueryable) {
        return $csvContentsQueryable->all('$v["Reg No."] != ' . $row['RegistrationNumber']);
    })->toArray();
    Log::info(sprintf("Soft deleting old records on '%s'", 'dealer'));
    from($oldRecords)->each(function ($row) use($database) {
        Log::info(sprintf("Deleting %s", $row['RegistrationNumber']));
        $database->update("dealer", array("LastChangeDateTimeUtc" => $database->sqleval("utc_timestamp()"), "IsDeleted" => 1), "Id=%s", $row["Id"]);
    });
    Log::info(sprintf("Inserting / updating records on '%s'", 'dealer'));
    from($csvContentsQueryable)->each(function ($record) use($database, $existingRecordsQueryable, $zipArchiveLocation) {
        $row = array("LastChangeDateTimeUtc" => $database->sqleval("utc_timestamp()"), "IsDeleted" => "0", "RegistrationNumber" => $record["Reg No."], "AttendeeNickname" => $record["Nick"], "DisplayName" => $record["Display Name"], "ShortDescription" => $record["Short Description"], "AboutTheArtistText" => $record["About the Artist"], "AboutTheArtText" => $record["About the Art"], "WebsiteUri" => $record["Website Reg"], "ArtPreviewCaption" => $record["Art Preview Caption"]);
        $zipContentsQueryable = getZipContentsAsQueryable($zipArchiveLocation);
        // Artist Thumbnail
        $artistThumbnailImageEntry = from($zipContentsQueryable)->where(function ($v) use($row) {