which book are not sold out in Book table and given Book name
| Book |
| BID | Bookname | pricecode |
| 1 | Harry potter | AB01 |
| 2 | Sheldon | AB01 |
| 3 | Dan brown | AB01 |
| 4 | Cindrella | AB01 |
| Sold |
| ID | BID | sold date |
| 1 | 1 | 9/13/2017 |
| 2 | 2 | 9/12/2017 |
| 3 | 4 | 9/15/2017 |
| 4 | 8 | 9/19/2017 |
select Bookname from Book Join sold on Book.BID=Sold.BID where sold date IS null
--i am not getting expected output