how to query in SQL with those multi condition? : ### table data(part) 
```
| user_id | count | create_time |
| ------- | ----- | ----------- |
| 10      | 20    | 2018-08-08  |
| 10      | 19    | 2018-08-09  |
| 2       | 15    | 2018-08-04  |
| 5       | 30    | 2018-08-10  |
```
### query conditions
**condition 1**: query result must order_by `count` desc

**condition 2**: `user_id` maybe repeat(for example: user_id=10)

**condition 3**: Each `user_id` has only one piece of data after the query

**condition 4**: the only one data from "condition 3" should be the one which `create_time` is most recent. In example, when `user_id=10`, the data's `create_time` should be "2018-08-09". (*this condition is optional*)

**condition 5**: limit 100