wordpress meta value compare between two date

After some research on wp codex I found my solution. Here I have to change birth_date format during save.
I saved value like yy-mm-dd this format and changed my meta_query

Here is the code

    $studentdata = get_users(
                array(
                    'meta_query'=> array(
                                       array(
                                          'key' => 'birth_date',
                                          'value'   => array(
                                               $startyear.'-01-01',$endyear.'-12-31'),
                                          'compare' => 'BETWEEN',
                                        )
                                    ),
                    'role'=>'student'
                )
            );  
print_r($studentdata);