Why in MySQL, we cannot use arithmetic operators like ‘=’, ‘<’ or ‘<>’ with NULL?

The reason behind it is that we will not receive any meaningful results from the comparisons when we use NULL with the comparison operators like ‘=’, ‘<’ or ‘<>’. Consider the following example which demonstrates this concept −

mysql> Select 10 = NULL, 10< NULL, 10<>NULL;
+-----------+----------+----------+
| 10 = NULL | 10< NULL | 10<>NULL |
+-----------+----------+----------+
|      NULL |     NULL |     NULL |
+-----------+----------+----------+
1 row in set (0.07 sec)

The above result set is not meaningful in any sense.