Group and Count Records in SQL Server

I had recently written a query to Select the Latest Record based on a Condition in SQL Server. A SQLServerCurry.com reader Mazz wrote back asking how to use the same query to count how many times a student took an exam for each course. Here’s the modified query that works on SQL Server 2005/2008.

SAMPLE DATA:

DECLARE @TT TABLE (CandID int, CourseID smallint)

INSERT INTO @TT VALUES (1, 101)
INSERT INTO @TT VALUES (3, 102)
INSERT INTO @TT VALUES (3, 110)
INSERT INTO @TT VALUES (3, 102)
INSERT INTO @TT VALUES (1, 101)
INSERT INTO @TT VALUES (2, 101)
INSERT INTO @TT VALUES (1, 110)
INSERT INTO @TT VALUES (1, 109)
INSERT INTO @TT VALUES (2, 102)
INSERT INTO @TT VALUES (1, 110)
INSERT INTO @TT VALUES (1, 101)
INSERT INTO @TT VALUES (3, 110)
INSERT INTO @TT VALUES (2, 102)
INSERT INTO @TT VALUES (2, 102)

QUERY

;WITH CTE
AS
(
SELECT
ROW_NUMBER() OVER (PARTITION BY CANDID, CourseID ORDER BY CandID) as ord,
CandID, CourseID
FROM @TT
)
SELECT CandID, CourseID, Count(CourseID) as TotalAttempts
FROM CTE
GROUP BY CandID, CourseID
ORDER BY CandID

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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