How to convert PREPARE sql query in to laravel?

I have done the mysql query but only problem i want to convert in laravel syntax. my output is coming very fine but i need to convert into laravel. Here is my below query:-

SET @sql = NULL;
    SELECT
      GROUP_CONCAT(DISTINCT
        CONCAT(
          'MAX(IF(size = ''',
          size,
          ''', qty, NULL)) AS ',
          size
        )
      ) INTO @sql
    FROM order_product_sizes;

    SET @sql = CONCAT('SELECT order_products.product_name, ', @sql, ' ,sum(qty) as total
                       FROM order_products join order_product_sizes
    on order_product_sizes.order_product_id = order_products.id
    group by order_product_sizes.order_product_id');

    PREPARE stmt FROM @sql;
    EXECUTE stmt;
    DEALLOCATE PREPARE stmt;

I have tried with DB::SELECT()..... but its not working. Can anyone help me. Thanks in advance .

via Chebli Mohamed