# 1107. New Users Daily Count

https://leetcode.com/problems/new-users-daily-count

## Description

Table: `Traffic`

```
+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| user\_id       | int     |
| activity      | enum    |
| activity\_date | date    |
+---------------+---------+
There is no primary key for this table, it may have duplicate rows.
The activity column is an ENUM type of ('login', 'logout', 'jobs', 'groups', 'homepage').
```

Write an SQL query that reports for every date within at most **90 days** from today, the number of users that logged in for the first time on that date. Assume today is **2019-06-30**.

The query result format is in the following example:

```
Traffic table:
+---------+----------+---------------+
| user\_id | activity | activity\_date |
+---------+----------+---------------+
| 1       | login    | 2019-05-01    |
| 1       | homepage | 2019-05-01    |
| 1       | logout   | 2019-05-01    |
| 2       | login    | 2019-06-21    |
| 2       | logout   | 2019-06-21    |
| 3       | login    | 2019-01-01    |
| 3       | jobs     | 2019-01-01    |
| 3       | logout   | 2019-01-01    |
| 4       | login    | 2019-06-21    |
| 4       | groups   | 2019-06-21    |
| 4       | logout   | 2019-06-21    |
| 5       | login    | 2019-03-01    |
| 5       | logout   | 2019-03-01    |
| 5       | login    | 2019-06-21    |
| 5       | logout   | 2019-06-21    |
+---------+----------+---------------+
Result table:
+------------+-------------+
| login\_date | user\_count  |
+------------+-------------+
| 2019-05-01 | 1           |
| 2019-06-21 | 2           |
+------------+-------------+
Note that we only care about dates with non zero user count.
The user with id 5 first logged in on 2019-03-01 so he's not counted on 2019-06-21.
```

## ac

```java
```
