i never found a free one, tho i think ninja forms (paid) may offer this.
the other option is write your own, or edit an existing plugin. most of those i looked at write each submission to a table, rather than overwrite old entries for the user’s id. that maybe coz wordpress (wpdb) doesn’t appear to have an easy sql function to ‘insert… or on duplicate update’ – so you’ll have to write one of those too using php with or without wpdb. here was my inefficient version – it makes 3 database requests per update:
$all_rows = $wpdb->get_results( $wpdb->prepare("SELECT * FROM ".$table." WHERE ".$id_field." = '".$value."'") );
$num_rows = $wpdb->num_rows;
if ($num_rows==0){ // insert new
$is_er = $wpdb->prepare($wpdb->insert($table, $data, $sql_data));
}
if ($num_rows==1){ // update if 1
$is_er =$wpdb->prepare($wpdb->update($table, $data, array($id_field => $value), $sql_data));//
}
...
or just purge the table of all existing entries for the id before you write
e.g.: $wpdb->query($wpdb->prepare(" DELETE FROM " . $table . " WHERE registration_id ='" . $registration_id."'"));
then of course you’ve got to get your answers out using sql… So it gets pretty ugly. I wish some clever plugin person could do it all for us
