511 Game Play Analysis I

Description

Table: Activity

• (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.

Problem Statement

Write an SQL query to report the first login date for each player.

Return the result table in any order.

The query result format is in the following example.

Example 1:

Input: Activity table:

Output:

Solution

Basically, we need to find the minimum value for event_date grouped by player_id. This can be done using aggregation with MIN() function.

1SELECT player_id, MIN(event_date) AS first_login
2    FROM Activity
3    GROUP BY player_id
4    ORDER BY player_id;