export mysql tables and zipArchive - php

Question

I've searched all the posts, but still couldn't get it to work. With button press I want to export "page preset" to be precise it's restaurant menu preset, it includes css files, mysql tables etc. I want to be able to import it to another 'menu'. First I'm trying to export mysql database. Should I use mysqldump or SELECT * INTO OUTFILE ?
I'm using this line:
exec("mysqldump --user=$dbusername --password=$dbpassword restaurantsdb meal --where=restaurant_id=$restId > tables/meal.sql");
restaurantsdb is database name and meal = table name. I also want rows WHERE 'restaurant_id' = {id}
I'm trying to understand how mysqldump works, should this line work for me?
Next I'm creating zipArchive file, adding some directories, I tried adding .txt file, that one works, but it doesn't seem to find meal.sql file.
$zip = new ZipArchive();
if ( $zip->open($zip_file, ZipArchive::CREATE) !== TRUE) {
exit("error");
}
$zip->addEmptyDir('TestFiles');
$zip->addEmptyDir('tables');
$fileToZip = __DIR__.'/hello.txt';
$zip->addFile($fileToZip, "TestFiles/text.txt");
$fileToZip = __DIR__.'/tables/meal.sql';
$zip->addFile($fileToZip, "tables/meal.sql");
$download_file = file_get_contents( $file_url );
$zip->addFromString(basename($file_url),$download_file);
$zip->close();
header('Content-type: application/zip');
header('Content-Disposition: attachment; filename="'.basename($zip_file).'"');
header("Content-length: " . filesize($zip_file));
header("Pragma: no-cache");
header("Expires: 0");
ob_clean();
flush();
readfile($zip_file);
unlink($zip_file);
exit;
Also, is it better to export as .sql or .csv ? Later when importing, I need to be able to change id's of all rows to specified, just before importing to database. It's basically cloning same data, but different id's.