#LC 550. Game Play Analysis IV
| 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.
Request: Write an SQL query to report the fraction of players that logged in again on the day after the day they first logged in, rounded to 2 decimal places. In other words, you need to count the number of players that logged in for at least two consecutive days starting from their first login date, then divide that number by the total number of players.
| player_id | device_id | event_date | games_played |
|---|---|---|---|
| 1 | 2 | 2016-03-01 | 5 |
| 1 | 2 | 2016-03-02 | 6 |
| 2 | 3 | 2017-06-25 | 1 |
| 3 | 1 | 2016-03-02 | 0 |
| 3 | 4 | 2018-07-03 | 5 |
| fraction |
|---|
| 0.33 |
Below is my code (SQL Server):
with cte1 as (
select a1.player_id as player_id
from activity a1
right join activity a2
on dateadd(day, 1, a1.event_date) = a2.event_date
)
select round(count(distinct cte1.player_id)/count(distinct activity.player_id), 2) as fraction
from activity, cte1
The result should be 0.33 but I got 0. Probably it's because select from two tables (which can work individually). Appreciate it if someone could help me understand why it's wrong. Thank you so much!
multiplying it by 1.0 will auto cast the count() (int) as decimal.
select round(count(distinct cte1.player_id) * 1.0/count(distinct activity.player_id) * 1.0, 2) as fraction
from activity, cte1