Select Clause MySQL

lue
mysql>
mysql>
mysql> SELECT 1 <=> NULL, 0 <=> NULL, NULL <=> NULL;
+------------+------------+---------------+
| 1 <=> NULL | 0 <=> NULL | NULL <=> NULL |
+------------+------------+---------------+
|          0 |          0 |             1 |
+------------+------------+---------------+
1 row in set (0.00 sec)