I have to create a membership site, but I need to give every user that registers a automatic ID number.

For example,

  • User 2 - has a code - pay-102

  • User 3 - has a code - pay-103

I did a forum search and found this, its pretty much what I am asking - What is the fastest way to generate a unique id number when registering a user

I've got a piece of code that will add it to the user panel in the admin area:

function fb_add_custom_user_profile_fields( $user ) {
<h3><?php _e('Extra Profile Informations', 'themename'); ?></h3>
<table class="form-table">
            <label for="memnumber"><?php _e('memnumber', 'themename'); ?>
            <input type="text" name="memnumber" id="memnumber" value="<?php echo esc_attr( get_the_author_meta( 'memnumber', $user->ID ) ); ?>" class="regular-text" /><br />
            <span class="description"><?php _e('Please enter your Membership number.', 'themename'); ?></span>
<?php }
function fb_save_custom_user_profile_fields( $user_id ) {
if ( !current_user_can( 'edit_user', $user_id ) )
    return FALSE;
update_usermeta( $user_id, 'memnumber', $_POST['memnumber'] );
add_action( 'show_user_profile', 'fb_add_custom_user_profile_fields' );
add_action( 'edit_user_profile', 'fb_add_custom_user_profile_fields' );
add_action( 'personal_options_update', 'fb_save_custom_user_profile_fields' );
add_action( 'edit_user_profile_update', 'fb_save_custom_user_profile_fields' );

How do I populate that field, with an incremental number that is assigned?

  • Hi Andy.. Not sure why you have to create an additional unique id for each user. Each registered user in WP already has a unique user id? I presume the users should not be able to edit their own user id, since that could create conflicts? Sep 20, 2012 at 10:52
  • I should also ask, if that field is populated from the wp_users database, and the 'admin' updated the number to a different one, would that update the database field -
    – Andy
    Sep 20, 2012 at 10:53
  • Hi Lars, The customer already has a numbering system for members, he has asked if it could continue in the same format (hopefully, just number change) - I personally don't see the point as its a strange request, but I'd like to know if it can be done, if it will cause any problems etc etc...
    – Andy
    Sep 20, 2012 at 10:55
  • Hi Andy. I added an answer with the code you need. If the customer has no particular reason for the request, I would not implement the code. But that is me :-) Sep 20, 2012 at 12:03

2 Answers 2


Here is some code that reads the highest number from the user meta table and then adds +1 to that number. This saves that number for each newly registered user. The code is triggered via the action hook "user_register".

add_action( 'user_register', 'assignuserid');

function assignuserid($user_id) {
   global $wpdb;
   $latestid=$wpdb->get_var("SELECT meta_value from $wpdb->usermeta where meta_key='memnumber' order by meta_value DESC limit 1;");
   update_user_meta( $user_id, 'memnumber', $latestid+1 );

Note: If the "pay-" is fixed, it does not need to be part of the code that stores the value, only part of the output. i.e:

echo "Your userid: PAY-"+$userid.

Here is a better solution:

add_filter("user_register", "get_unique");
function get_unique($user_id){
    $prefix = "PAY-";
    do {
        $unique = mt_rand();
        $unique = substr($unique, 0, 3);
        $unique = $prefix . $unique;
    } while (!check_unique($unique));
    return update_usermeta( $user_id, 'memnumber', $unique );//$unique;
function check_unique($unique) {
    global $wpdb;
    $result = $wpdb->get_var("SELECT meta_value from $wpdb->usermeta where meta_key='memnumber' AND meta_value = '$unique'");
        return true;
    return false;
  • 2
    Please add an explanation to your answer: why could that solve the problem?
    – fuxia
    Sep 27, 2014 at 1:39

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