Shows how to record the user ID of the person editing a Participants Database record

pdb-record-last-user.php

<?php
add_action( 'pdb-after_submit_update', 'xnau_record_last_user' );
/**
 * record the user who created or edited a record in the backend
 * 
 * @see https://codex.wordpress.org/Function_Reference/wp_get_current_user
 *
 * @param array $record the record data
 */
function xnau_record_last_user( $record )
{
  $current_user = wp_get_current_user();
  if ( $current_user->ID != '0' ) {
    $user_id_field = 'user_id'; // name of the PDB field where the user's ID is stored
    global $wpdb;
    // you could also record the user's login or name...see the link above for what you can get from $surrent_user
    $data = array( $user_id_field => $current_user->ID ); // get the user's ID and place it in the ID field
    $wpdb->update( Participants_Db::$participants_table, $data, array( 'id' => $record['id'] ) );
  }
}