------+
| (5 * 2) = CONCAT('1', '0') |
+----------------------------+
|                          1 |
+----------------------------+

SELECT 1 = NULL;
+----------+
| 1 = NULL |
+----------+
|     NULL |
+----------+

SELECT NULL = NULL;
+-------------+
| NULL = NULL |
+-------------+
|        NULL |
+-------------+

URL: https://mariadb.com/kb/en/equal/https://mariadb.com/kb/en/equal/