NULL в SQL

SELECT 1 + NULL, CONCAT(1, NULL), CONCAT_WS(',', 1, NULL), AVG(v), COUNT(*), MIN(v) FROM (SELECT 1 AS v UNION ALL SELECT NULL AS v) AS t1;

В виде текста:

+----------+-----------------+-------------------------+--------+----------+--------+
| 1 + NULL | CONCAT(1, NULL) | CONCAT_WS(',', 1, NULL) | AVG(v) | COUNT(*) | MIN(v) |
+----------+-----------------+-------------------------+--------+----------+--------+
|     NULL | NULL            | 1                       | 1.0000 |        2 |      1 |
+----------+-----------------+-------------------------+--------+----------+--------+