Rank Visits SQL Server 2014 - sql

Question

I have a sample table of doctor visits by ID. I'm looking to rank the problems by age, partitioned by ID so I can do some statistic calculations on the 2nd and 3rd visit of the same problem by ID. Please Note: I have a larger dataset so i'm looking for something that will handle that.
So far I have
SELECT
ID, Age, Problem, COUNT(Problem) AS cnt,
RANK() OVER (PARTITION BY id ORDER BY Problem, Age ASC) AS rnk
FROM
#Test1
GROUP BY
ID, Problem, Age
ORDER BY
Age ASC
The code runs but the rank is not properly calculated. Please help.

Answer 1

As I understand, you need partition by ID and Problem:
CREATE TABLE #Test1 (ID int, Problem nvarchar(20), Age int)
INSERT INTO #Test1
VALUES
(1,'Arm',50),
(1,'Arm',52),
(1,'Foot',54),
(1,'Tongue',55),
(1,'Arm',59),
(2,'Toe',60),
(2,'Toe',60),
(2,'Arm',61),
(3,'Tooth',75),
(3,'Tooth',76),
(3,'Knee',78)
SELECT
ID,
Age,
Problem,
COUNT(*) OVER (PARTITION BY ID, Problem, Age) as cnt,
RANK() OVER (PARTITION BY ID, Problem ORDER BY Age) as rnk
FROM #Test1 AS t
ORDER BY t.Age
DROP TABLE #Test1
In this solution you will get the same rank = 1 for data (2,'Toe',60). To enumerate them, replace RANK with ROW_NUMBER

Answer 2

I believe you want row_number() instead of rank():
select
id
, Age
, Problem
, cnt = count(*) over (partition by id, Problem)
, rnk = row_number() over (partition by id, Problem order by Age)
from t
order by id, Age, Problem
test setup: http://rextester.com/DUWG50873
returns:
+----+-----+---------+-----+-----+
| id | Age | Problem | cnt | rnk |
+----+-----+---------+-----+-----+
| 1 | 50 | Arm | 3 | 1 |
| 1 | 52 | Arm | 3 | 2 |
| 1 | 54 | Foot | 1 | 1 |
| 1 | 55 | Tongue | 1 | 1 |
| 1 | 59 | Arm | 3 | 3 |
| 2 | 60 | Toe | 2 | 1 |
| 2 | 60 | Toe | 2 | 2 |
| 2 | 61 | Arm | 1 | 1 |
| 3 | 75 | Tooth | 2 | 1 |
| 3 | 76 | Tooth | 2 | 2 |
| 3 | 78 | Knee | 1 | 1 |
+----+-----+---------+-----+-----+