WP_List_Table No Data being displayed

I am trying to use wp_list table to display my data in the plugin however its showing no data i am using the following. There is def test data is their any php editor that lest u debug like visual studio btw.

class TT_Example_List_Table extends WP_List_Table {



  function __construct(){
    global $status, $page;

    //Set parent defaults
    parent::__construct( array(
        'singular'  => 'realtyna',     //singular name of the listed records
        'plural'    => 'realtyna',    //plural name of the listed records
        'ajax'      => false        //does this table support ajax?
    ) );

}

 function prepare_items() {
        global $wpdb; //This is used only if making any database queries
        $per_page = 5;
        $columns = $this->get_columns();
        $hidden = array();
        $sortable = $this->get_sortable_columns();
        $columns = $this->get_columns();
        $data = $wpdb->get_results("SELECT * FROM realtyna");
        $hidden = array();
        $sortable = $this->get_sortable_columns();
        $this->_column_headers = array($columns, $hidden, $sortable);
        $data = array_slice($data,(($current_page-1)*$per_page),$per_page);             
        $current_page = $this->get_pagenum();
        $this->items = $data;




            /**
         * REQUIRED. We also have to register our pagination options & calculations.
         */
        $this->set_pagination_args( array(
            'total_items' => $total_items,                  //WE have to calculate the total number of items
            'per_page'    => $per_page,                     //WE have to determine how many items to show on a page
            'total_pages' => ceil($total_items/$per_page)   //WE have to calculate the total number of pages
        ) );
 }

 function column_default($item, $column_name){
        switch($column_name){
            case 'name':
            case 'phone':
                return $item[$column_name];
            default:
                return print_r($item,true); //Show the whole array for troubleshooting purposes
        }
    }
    function get_columns(){
        $columns = array(
            'name'     => 'name',
            'email'    => 'email',
            'phone'  => 'phone'
        );
        return $columns;
    }

    function get_sortable_columns() {
        $sortable_columns = array(
            'name'     => array('name',false),     //true means it's already sorted
            'email'    => array('email',false),
            'phone'  => array('phone',false)
        );
        return $sortable_columns;
    }

}