Remove multiple rows with same ID - sql

Question

So I've done some looking around and wasn't unable to find quite what I was looking for. I have two tables.
1.) Table where general user information is stored
2.) Where a status is generated and stored.
The problem is, is that there are multiple rows for the same users and querying these results in multiple returns. I can't just merge them because they aren't all the same status. I need just the newest status from that table.
Example of the table:
SELECT DISTINCT
TOP(50) cam.UserID AS PatientID,
mppi.DisplayName AS Surgeon,
ISNULL(sci.IOPStatus, 'N/A') AS Status,
tkstat.TrackerStatusID AS Stat_2
FROM
Main AS cam
INNER JOIN
Providers AS rap
ON cam.VisitID = rap.VisitID
INNER JOIN
ProviderInfo AS mppi
ON rap.UnvUserID = mppi.UnvUserID
LEFT OUTER JOIN
Inop AS sci
ON cam.CwsID = sci.CwsID
LEFT OUTER JOIN
TrackerStatus AS tkstat
ON cam.CwsID = tkstat.CwsID
WHERE
(
cam.Location_ID IN
(
'SURG'
)
)
AND
(
rap.IsAttending = 'Y'
)
AND
(
cam.DateTime BETWEEN CONCAT(CAST(GETDATE() AS DATE), ' 00:00:00') AND CONCAT(CAST(GETDATE() AS DATE), ' 23:59:59')
)
AND
(
cam.Status_StatusID != 'Cancelled'
)
ORDER BY
cam.UserID ASC
So I need to grab only the newest Stat_2 from each ID so they aren't returning multiple rows. Each Stat_2 also has an update time meaning I can sort by the time/date that column is : StatusDateTime

Answer 1

One way to handle this is to create a calculated row_number for the table where you need the newest record.
Easiest way to do that is to change your TKSTAT join to a derived table with the row_number calculation and then add a constraint to your join where the RN =1
SELECT DISTINCT TOP (50)
cam.UserID AS PatientID, mppi.DisplayName AS Surgeon, ISNULL(sci.IOPStatus, 'N/A') AS Status, tkstat.TrackerStatusID AS Stat_2
FROM Main AS cam
INNER JOIN Providers AS rap ON cam.VisitID = rap.VisitID
INNER JOIN ProviderInfo AS mppi ON rap.UnvUserID = mppi.UnvUserID
LEFT OUTER JOIN Inop AS sci ON cam.CwsID = sci.CwsID
LEFT OUTER JOIN (SELECT tk.CwsID, tk.TrackerStatusId, ROW_NUMBER() OVER (PARTITION BY tk.cwsId ORDER BY tk.CreationDate DESC) AS rn FROM TrackerStatus tk)AS tkstat ON cam.CwsID = tkstat.CwsID
AND tkstat.rn = 1
WHERE (cam.Location_ID IN ( 'SURG' )) AND (rap.IsAttending = 'Y')
AND (cam.DateTime BETWEEN CONCAT(CAST(GETDATE() AS DATE), ' 00:00:00') AND CONCAT(CAST(GETDATE() AS DATE), ' 23:59:59'))
AND (cam.Status_StatusID != 'Cancelled')
ORDER BY cam.UserID ASC;
Note you need a way to derive what the "newest" status is; I assume there is a created_date or something; you'll need to enter the correct colum name
ROW_NUMBER() OVER (PARTITION BY tk.cwsId ORDER BY tk.CreationDate DESC) AS rn

Answer 2

SQL Server doesn't offer a FIRST function, but you can reproduce the functionality with ROW_NUMBER() like this:
With Qry1 (
Select <other columns>,
ROW_NUMBER() OVER(
PARTITION BY <group by columns>
ORDER BY <time stamp column*> DESC
) As Seq
From <the rest of your select statement>
)
Select *
From Qry1
Where Seq = 1
* for the "newest" record.