PHP Unique random string generator

Question

How to make a random string unique to the string in the column below?

<?php
$n=10;
function getName($n) {
    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $randomString = '';

    for ($i = 0; $i < $n; $i++) {
        $index = rand(0, strlen($characters) - 1);
        $randomString .= $characters[$index];
    }

    return $randomString;
}

echo getName($n);
?>

Does this answer your question? [PHP/MySQL - Best way to create unique random string?](https://stackoverflow.com/questions/7893257/php-mysql-best-way-to-create-unique-random-string) — user3783243, Mar 06 '22 at 12:16
Yes, But sometimes it will randomize the already existing string causing an error when saving. — Noso Sanas, Mar 06 '22 at 12:28
You mean you randomize the random string? Not sure I know what you mean.. whats the error? — user3783243, Mar 06 '22 at 12:34
If I want to randomize one number from "1,2,3", But there is already a row with the value 2 in the "String" column, the random value must be either 1 or 3. — Noso Sanas, Mar 06 '22 at 12:40
That is unique, not random.. What error are you receiving? Value already exists? — user3783243, Mar 06 '22 at 12:42

score 0 · Answer 1 · answered Mar 06 '22 at 12:07

<?php
    $n = 10;
    function getName($n) {
        $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
        $randomString = '';
        for ($i = 0; $i < $n; $i++) {
            $index = rand(0, strlen($characters) - 1);
            $randomString .= $characters[$index];
        }
        return $randomString;
    }
    function getUniqueString($length, $dbConnection){
        $string = getName($length);
        $count  = $dbConnection->query("SELECT * FROM TABLE_NAME WHERE string='$string')")->num_rows;
        while($count != 0){
            $string = getName($length);
            $count  = $dbConnection->query("SELECT * FROM TABLE_NAME WHERE string='$string')")->num_rows;
        }
        return $string;
    }

    echo getUniqueString($n, $dbConnection);
?>

If the table name is "test', how should I add the table name? — Noso Sanas, Mar 06 '22 at 12:29

score 0 · Answer 2 · answered Mar 06 '22 at 14:26

0

You can use openssl_random_pseudo_bytes() or random_bytes() PHP fonction to generate random strings.

You can also rely on MySQL to generate uniq IDs :

INSERT INTO mytable (alphaID) VALUES (REPLACE( UUID(), '-', '' ));

answered Mar 06 '22 at 14:26

Alaindeseine

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PHP Unique random string generator

2 Answers2