I want to generate a unique hash/number that I can use for status tracking for an contest. I'm going to use this hash/number in a url created with add_query_args.

The url creation will look something like this:

$url = add_query_arg( array( 'id' => 'tracking_number_comes_here', 'email' => '$contest_object->email' ), $redirect_url );

That will output something like this:


This is working fine, but I'm having a hard way to generate a unique hash/number to use as the tracking number.

A row is added to contest table when a participant submits his participation. I use wpdb to insert to my table:

    // Add user to db
    $addRow = $wpdb->insert(
                'name' => $data['name'],    
                'email' => $data['email'],
                'shared_facebook' => 0,
                'shared_mail' => 0,
                'tracking' => $unique_hash_number

I think generating an 8 character hash from an integer with md5 were the integer is the participant ID will work.

$hash = substr(md5($id), 0, 8);

Is it possible to grab the participant id on insertion? or do I have to update the hash after the participant is added to the table?

1 Answer 1


The userid will not exist until the user is inserted, you would need to do a second update for that. You may be better off using PHP's uniqid(), perhaps with the user's email as a salt/prefix to avoid a race condition (however unlikely).

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