Select the Latest Record based on a Condition in SQL Server

I was working on a query recently and thought of sharing the solution with all my readers. Here’s the problem statement - An institute allows its students to appear for an exam twice, for each course they attend. While generating the report, the institute wanted that only the latest exam date should be shown, listing the CandidateID, CourseID and latest ExamDate for that Student in each Course. The query works on SQL Server 2005/2008.

SAMPLE DATA

DECLARE @TT TABLE (CandID int, CourseID smallint, DateOfExam datetime)

INSERT INTO @TT VALUES (1, 101, 'April 02, 2010 11:25am')
INSERT INTO @TT VALUES (3, 102, 'April 03, 2010 9:55am')
INSERT INTO @TT VALUES (5, 110, 'April 07, 2010 11:24am')
INSERT INTO @TT VALUES (3, 102, 'April 10, 2010 11:22am')
INSERT INTO @TT VALUES (4, 109, 'April 15, 2010 5:27am')
INSERT INTO @TT VALUES (2, 101, 'April 16, 2010 8:21am')
INSERT INTO @TT VALUES (1, 110, 'April 17, 2010 11:55am')
INSERT INTO @TT VALUES (4, 109, 'April 22, 2010 10:16am')
INSERT INTO @TT VALUES (6, 102, 'April 24, 2010 11:35am')
INSERT INTO @TT VALUES (1, 110, 'April 30, 2010 9:49pm')
INSERT INTO @TT VALUES (1, 101, 'May 01, 2010 9:49am')
INSERT INTO @TT VALUES (5, 110, 'May 02, 2010 10:43am')
INSERT INTO @TT VALUES (2, 101, 'May 03, 2010 11:29am')
INSERT INTO @TT VALUES (6, 102, 'May 03, 2010 11:29am')

QUERY

;WITH CTE
AS
(
SELECT
ROW_NUMBER() OVER (PARTITION BY CandID, CourseID order by DateOfExam DESC) as ord,
CandID, CourseID, DateOfExam
FROM @TT
)
SELECT CandID, CourseID, DateOfExam
FROM CTE
WHERE ord = 1;
GO

As you can see, we use the ROW_NUMBER() function to calculate the sequential number of a row within a partition of each CandidateID and CourseID and then use ord=1 to select the latest date

OUTPUT

About The Author

Suprotim Agarwal, MCSD, MCAD, MCDBA, MCSE, is the founder of DotNetCurry, DNC Magazine for Developers, SQLServerCurry and DevCurry. He has also authored a couple of books 51 Recipes using jQuery with ASP.NET Controls and a new one recently at The Absolutely Awesome jQuery CookBook.

Suprotim has received the prestigous Microsoft MVP award for nine times in a row now. In a professional capacity, he is the CEO of A2Z Knowledge Visuals Pvt Ltd, a digital group that represents premium web sites and digital publications comprising of Professional web, windows, mobile and cloud developers, technical managers, and architects.

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