mysql> SELECT * FROM calls;mysql> SELECT * FROM calls;
+----+------------+---------+--------+
| id | 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   |
+----+------------+---------+--------+