Simplify SQL select statement

Question

I have table with such structure

CREATE TABLE UsersHistory
(
    Id          INT IDENTITY,
    UserID      INT,
    StatusId    INT,
    CreateTime  DATETIME,
    ChangedTime DATETIME
)

INSERT INTO UsersHistory(UserID, StatusId, CreateTime, ChangedTime)
SELECT 1,1,'20150414','20150414' UNION ALL
SELECT 1,2,'20150414','20150415' UNION ALL
SELECT 1,3,'20150414','20150416' UNION ALL
SELECT 2,1,'20150413','20150413' UNION ALL
SELECT 2,3,'20150413','20150416'

and query

;WITH k AS (
SELECT uh.UserID,MAX(uh.ChangedTime) AS Dt FROM UsersHistory AS uh
WHERE uh.ChangedTime<'20150416'
GROUP BY uh.UserID
)
SELECT k.UserID,uh.StatusId FROM k
INNER JOIN UsersHistory AS uh
    ON k.UserID = uh.UserID AND k.Dt = uh.ChangedTime

Query is too easy and not needs more explanation. I want to simplify my it. (Remove join with datetime type column).

Any Suggestion?

Answer 1

You can use ROW_NUMBER() with PARTITION to achieve this. Something like this

;WITH CTE as 
( 
    SELECT UserID, StatusId, CreateTime, ChangedTime,ROW_NUMBER()OVER(PARTITION BY UserID ORDER BY ChangedTime DESC) r
    FROM UsersHistory
    WHERE ChangedTime < '20150416'
)
SELECT UserID, StatusId FROM CTE
WHERE r = 1