+----+------------+---------+--------+
|sid | date | user_id |license |
+----+------------+---------+--------+
| 1 | 2016-06-22 | 1 | he |
| 2 | 2016-06-22 | NULL | do |
| 3 | 2016-06-22 | NULL | as |
| 4 | 2016-06-23 | 2 | to |
| 5 | 2016-06-23 | 1 | we |
| 6 | 2016-06-23 | 1 | be |
| 7 | 2016-06-23 | NULL | go |
+----+------------+---------+--------+
Использовать этот:
UPDATE `calls` SET `date` = NULL, `user_id` = NULL
Других решений пока нет …