How to identify entries that have not changed over time? - mysql

Question

I am trying to identify names that have not had a total score change over a period of time, and what that period of time was.
Example Table:
+----------+--------+-------+
| Date | Name | Score |
+----------+--------+-------+
| 1/1/2016 | Frank | 55 |
| 1/1/2016 | John | 80 |
| 1/2/2016 | Frank | 60 |
| 1/2/2016 | John | 85 |
| 1/3/2016 | Frank | 60 |
| 1/3/2016 | John | 100 |
| 1/4/2016 | Frank | 60 |
| 1/4/2016 | John | 120 |
| 1/5/2016 | Frank | 60 |
| 1/5/2016 | John | 120 |
+----------+--------+-------+
Expected Output:
+-------+------+
| Name | Days |
+-------+------+
| Frank | 4 |
| John | 2 |
+-------+------+
I have been trying to puzzle out how to do this with no success. I have no code to show since none of it has even been close to successful and would only serve to clutter up the question.
How can I go about doing this?

Answer 1

You need to group the data with the score, and then calculate the first and last day that the user has that score, check this:
SELECT DATEDIFF(last_day, first_day) + 1 AS days, name, score,
first_day, last_day
FROM (
SELECT
max(date_score) as last_day,
min(date_score) as first_day,
score,
name
FROM members
GROUP by score
) AS score
The Date diff function return the difference between two DATE's, we add one to represent that the score last one day.
Check here for a working example link