How to get last updated row or ID in wordpress

I had the same problem.

There is no equivalent function. $wpdb->insert_id works only after $wpdb->insert

Alternative way

If it’s an update, you can either get the id with a query based on the data you have got, or most of the time, you should have already got the id before update it.

global $wpdb;

$data = array(
    'first_name' => "John",
    'last_name' => "Doe"
);

$where = array(
    'id' => $my_id
);

$res_update = $wpdb->update( $wpdb->prefix . "my_table", $data, $where );

if( $res_update === false ){
     error_log( 'my error');
}

return $my_id;