SQL Query Find x rows forward the highest value without having a lower value in between - sql

Question

I have a table with the left 2 columns.
I am trying to achieve the 3th column based on some logic.
Logic: If we take date 1/1 and go further the highest score that wil be reached with going further in dates before the score goes down will be on 3/1. With a score of 12. So as HighestAchievedScore we will retrieve 12 for 1/1. And so forth.
If we are on a date where the next score goes down my highestAchieveScore will be my next score. Like you can see at 3/01/2014
date score HighestAchieveScore
1/01/2014 10 12
2/01/2014 11 12
3/01/2014 12 10
4/01/2014 10 11
5/01/2014 11 9
6/01/2014 9 8
7/01/2014 8 9
8/01/2014 9 9
I hope I explained it clear enough.
Thanks already for every input resolving the problem.

Answer 1

Lets make some test data:
DECLARE #Score TABLE
(
ScoreDate DATETIME,
Score INT
)
INSERT INTO #Score
VALUES
('01-01-2014', 10),
('01-02-2014', 11),
('01-03-2014', 12),
('01-04-2014', 10),
('01-05-2014', 11),
('01-06-2014', 9),
('01-07-2014', 8),
('01-08-2014', 9);
Now we are going to number our rows and then link to the next row to see if we are still going up
WITH ScoreRows AS
(
SELECT
s.ScoreDate,
s.Score,
ROW_NUMBER() OVER (ORDER BY ScoreDate) RN
FROM #Score s
),
ScoreUpDown AS
(
SELECT p.ScoreDate,
p.Score,
p.RN,
CASE WHEN p.Score < n.Score THEN 1 ELSE 0 END GoingUp,
ISNULL(n.Score, p.Score) NextScore
FROM ScoreRows p
LEFT JOIN ScoreRows n
ON n.RN = p.RN + 1
)
We take our data recursively look for the next row that is right before a fall, and take that value as our max for any row that is still going up. otherwise, we use the score for the next falling row.
SELECT
s.ScoreDate,
s.Score,
CASE WHEN s.GoingUp = 1 THEN d.Score ELSE s.NextScore END Test
FROM ScoreUpDown s
OUTER APPLY
(
SELECT TOP 1 * FROM ScoreUpDown d
WHERE d.ScoreDate > s.ScoreDate
AND GoingUp = 0
) d;
Output:
ScoreDate Score Test
2014-01-01 00:00:00.000 10 12
2014-01-02 00:00:00.000 11 12
2014-01-03 00:00:00.000 12 10
2014-01-04 00:00:00.000 10 11
2014-01-05 00:00:00.000 11 9
2014-01-06 00:00:00.000 9 8
2014-01-07 00:00:00.000 8 9
2014-01-08 00:00:00.000 9 9

Answer 2

Assuming you are wanting the third column to be computed, you can create the table like this (or add the column to an existing table), using a function to determine the value of the third column:
Create Function dbo.fnGetMaxScore(#Date Date)
Returns Int
As Begin
Declare #Ret Int
Select #Ret = Max(Score)
From YourTable
Where Date > #Date
Return #Ret
End
Create Table YourTable
(
Date Date,
Score Int,
HighestAchieveScore As dbo.fnGetMaxScore(Date)
)

Answer 3

I'm not sure this will work.... but this is the general concept.
Self join on A.Date < B.Date to get max score, but use coalesce and a 3rd self join on a rowID assigned in a CTE to determine if the score dropped on the next record, and if it did coalesce that score in, otherwise use the max score.
NEED TO TEST but have to setup a fiddle to do so..
WITH CTE as
(SELECT Date, Score, ROW_NUMBER() OVER(ORDER BY A.Date ASC) AS Row FROM tableName)
SELECT A.Date, A.Score, coalesce(c.score, Max(A.Score)) as HighestArchievedScore
FROM CTE A
LEFT JOIN CTE B
on A.Date < B.Date
LEFT JOIN CTE C
on A.Row+1=B.Row
and A.Score > C.Score
GROUP BY A.DATE,
A.SCORE

Answer 4

This should work on SQL Server 2012 but not earlier versions:
WITH cte AS (
SELECT date,
LEAD(score) OVER (ORDER BY date) nextScore
FROM yourTable
)
SELECT t.date, score,
CASE
WHEN nextScore < score THEN nextScore
ELSE (
SELECT ISNULL(MAX(t1.score), t.score)
FROM yourTable t1
JOIN cte ON t1.date = cte.date
WHERE t1.date > t.date
AND ISNULL(nextScore, 0) < score
)
END AS HighestAchieveScore
FROM yourTable t
JOIN cte ON t.date = cte.date