我有一个名为客户的表来保存客户的数据
id | fname | lname
--- | ------ | ------
1 | John | Smith
2 | Mike | Bolton
3 | Liz | John
4 | Mark | Jobs
我还有另一个名为call的表,可以对每个客户进行每次调用.
id | timestamp | customer_id | campaign | answered |
1 |2016-09-05 15:24:08| 1 | 2016-09 | 1 |
2 |2016-09-05 15:20:08| 2 | 2016-09 | 1 |
3 |2016-08-05 15:20:08| 2 | 2016-08 | 1 |
4 |2016-08-05 13:20:08| 3 | 2016-08 | …