Написано: 27.03.2023

511. Анализ игры I (Game Play Analysis I)

easy

SQL schema

Table: activity

+--------------+---------+
| Column Name  | Type    |
+--------------+---------+
| player_id    | int     |
| device_id    | int     |
| event_date   | date    |
| games_played | int     |
+--------------+---------+
(player_id, event_date) is the primary key of this table.
This table shows the activity of players of some games.
Each row is a record of a player who logged in and played a number of games (possibly 0) before logging out on someday using some device.

Задание.

Напишите SQL-запрос, чтобы сообщить дату первого входа в систему для каждого игрока.

Верните таблицу результатов в любом порядке.

Формат результата запроса приведен в следующем примере.

Пример 1.

Входные данные:

Activity table:
+-----------+-----------+------------+--------------+
| player_id | device_id | event_date | games_played |
+-----------+-----------+------------+--------------+
| 1         | 2         | 2016-03-01 | 5            |
| 1         | 2         | 2016-05-02 | 6            |
| 2         | 3         | 2017-06-25 | 1            |
| 3         | 1         | 2016-03-02 | 0            |
| 3         | 4         | 2018-07-03 | 5            |
+-----------+-----------+------------+--------------+

Результат:

+-----------+-------------+
| player_id | first_login |
+-----------+-------------+
| 1         | 2016-03-01  |
| 2         | 2017-06-25  |
| 3         | 2016-03-02  |
+-----------+-------------+

Решение.

/* Write your PL/SQL query statement below */
SELECT player_id, TO_CHAR(MIN(event_date), 'YYYY-MM-DD') AS first_login FROM activity GROUP BY player_id