Random UserID in PHP and MySQL - php

Question

I have a PHP project in which i want to create and assign random User IDs to my customers when they sign-up in to our company's second website. It must be random generated user Ids that must not duplicate in our MySQL Database. User IDs should be like XYZ654986, HPR654986, WRU934765, SYW365824.
How can I create , check and insert user IDs like these ?

Answer 1

First of all, while random IDs for public services (like YouTube Video IDs) in the URL are useful, internally you shouldn't use random IDs. An ID which is used only backend could be made with AutoIncrement.
Nevertheless, you could have specific reasons to use a random ID.
First, you need to create a random code.
This creates a random code with the length 10 (you can change the length by changing $i<10):
$char = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";
$chars = explode ( ",", $char );
$code = "";
for ($i=0; $i<10; $i++) {
$random = rand(0, (count($chars)-1));
$code .= $chars[$random];
}
Then, you need to check whether the code is already used or not.
If you have the codes in your MySQL database, you can use this:
$EveryID = array();
$statement = $pdo->prepare("SELECT ID FROM MyDatabase");
$statement->execute();
while($row = $statement->fetch()) {
array_push($EveryID, $row["ID"]);
}
$IDexists = false;
for ($i=0; $iy<count($EveryID), $i++) {
if ($EveryID[$i] == $code) {
$IDexists = true;
break;
}
}
And if $IDexists is true, you need to do the same (generate new code, etc.). I would do this with a while loop.
If $IDexists is false, you have a new unused code in $code. Then, you need to insert this code with other user information (e.g. name).
Here the full code:
$IDexists = true;
while ($IDexists == true) {
$char = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";
$chars = explode ( ",", $char );
$code = "";
for ($i=0; $i<10; $i++) {
$random = rand(0, (count($chars)-1));
$code .= $chars[$random];
}
$EveryID = array();
$statement = $pdo->prepare("SELECT ID FROM MyDatabase");
$statement->execute();
while($row = $statement->fetch()) {
array_push($EveryID, $row["ID"]);
}
$IDexists = false;
for ($i=0; $iy<count($EveryID), $i++) {
if ($EveryID[$i] == $code) {
$IDexists = true;
break;
}
}
}
$statement = $pdo->prepare("INSERT INTO MyDatabase (ID, name, something) VALUES (:ID, :name, :sth)");
$statement->execute(array("ID" => $code, "Name" => $name, "sth" => $Something));
Requirements for this method are that you've made a PDO connection with your database at the beginning of your .php file. If you haven't made that, just google "php MySQL PDO" and look at a tutorial.
At last, I just want to say: If you use the IDs internally (that means the IDs aren't in the URL to the user's site), I'd recommend to make an Auto-Increment ID (that means, the first user has the ID 1, the second 2, etc.). You can set the ID in PhpMyAdmin as primary and check auto-Incrediment to do this (there are tutorials for this, too). That's way easier and for most use-cases more practical (but only if the IDs aren't in the URL on any place on your site).
Edit: Instead of
while($row = $statement->fetch()) {
array_push($EveryID, $row["ID"]);
}
you can use
$EveryID = $statement->fetchAll();