SQL Server: Count based on Condition

Many a times, you may want to do a count in SQL Server, based on a condition. The easiest way is to use a combination of SUM and CASE as shown in this example

count with condition

Here’s the same query to try out

DECLARE @TT Table (
CourseID int, StudentID int, EnrolledBy varchar(25)
)

INSERT INTO @TT
SELECT 1, 1, 'Hrishi' UNION ALL
SELECT 1, 2, 'Sagar' UNION ALL
SELECT 1, 3, 'Tony' UNION ALL
SELECT 1, 2, 'James' UNION ALL
SELECT 1, 4, 'Krish' UNION ALL
SELECT 2, 5, 'Tony' UNION ALL
SELECT 2, 5, 'Molly' UNION ALL
SELECT 2, 6, 'Tony'


SELECT
COUNT(*) as 'Total Enrolled',
SUM(CASE
WHEN EnrolledBy = 'Tony'
THEN 1 ELSE 0 END) as 'EnrolledbyTony'
FROM
@TT

In the query shown above, we are using SUM and CASE to count data only for those records, which are Enrolled by Tony. Similarly instead of SUM, you can also use COUNT which only counts the non-null values.

OUTPUT

image


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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1 comment:

Sarath said...

count database on condition is very help full article for me, But I have rise bit problem with this articles about some conditions you can read following article and get more suggestion about your condition, It is Sql tutorial