How to generate unique random value for each user in laravel and add it to database

You can use php's uniqid() function to generate a unique ID based on the microtime (current time in microseconds)

Example:

<?phpecho uniqid();?>

Output:

56c3096338cdb

Your logic isn't technically faulty. However, if your application attracts lots of users, fetching all of the random numbers may well become unnecessarily expensive, in terms of resources and computation time.

I would suggest another approach, where you generate a random number and then check it against the database.

function generateBarcodeNumber() {    $number = mt_rand(1000000000, 9999999999); // better than rand()    // call the same function if the barcode exists already    if (barcodeNumberExists($number)) {        return generateBarcodeNumber();    }    // otherwise, it's valid and can be used    return $number;}function barcodeNumberExists($number) {    // query the database and return a boolean    // for instance, it might look like this in Laravel    return User::whereBarcodeNumber($number)->exists();}

This is good:

do {   $refrence_id = mt_rand( 1000000000, 9999999999 );} while ( DB::table( 'transations' )->where( 'RefrenceID', $refrence_id )->exists() );