Difference between where and having in sql server

sql server where vs having
sql server group by where having
group by having sql server

In this vide we will discuss the difference between where and having caluses in sql server.

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Let us understand the difference with an example.

To calculate total sales by product, we would write a GROUP BY query as shown below
SELECT Product, SUM(SaleAmount) AS TotalSales
FROM Sales
GROUP BY Product

Now if we want to find only those products where the total sales amount is greater than $1000, we will use HAVING clause to filter products
SELECT Product, SUM(SaleAmount) AS TotalSales
FROM Sales
GROUP BY Product
HAVING SUM(SaleAmount) ] 1000

If we use WHERE clause instead of HAVING clause, we will get a syntax error. This is because the WHERE clause doesn’t work with aggregate functions like sum, min, max, avg, etc.
SELECT Product, SUM(SaleAmount) AS TotalSales
FROM Sales
GROUP BY Product
WHERE SUM(SaleAmount) ] 1000

So in short, the difference is WHERE clause cannot be used with aggregates where as HAVING can.

However, there are other differences as well that we need to keep in mind when using WHERE and HAVING clauses. WHERE clause filters rows before aggregate calculations are performed where as HAVING clause filters rows after aggregate calculations are performed. Let us understand this with an example.

Total sales of iPhone and Speakers can be calculated by using either WHERE or HAVING clause

Calculate Total sales of iPhone and Speakers using WHERE clause : In this example the WHERE clause retrieves only iPhone and Speaker products and then performs the sum.
SELECT Product, SUM(SaleAmount) AS TotalSales
FROM Sales
WHERE Product in ('iPhone', 'Speakers')
GROUP BY Product

Calculate Total sales of iPhone and Speakers using HAVING clause : This example retrieves all rows from Sales table, performs the sum and then removes all products except iPhone and Speakers.
SELECT Product, SUM(SaleAmount) AS TotalSales
FROM Sales
GROUP BY Product
HAVING Product in ('iPhone', 'Speakers')

So from a performance standpoint, HAVING is slower than WHERE and should be avoided when possible.

Another difference is WHERE comes before GROUP BY and HAVING comes after GROUP BY.

Difference between WHERE and Having
1. WHERE clause cannot be used with aggregates where as HAVING can. This means WHERE clause is used for filtering individual rows where as HAVING clause is used to filter groups.
2. WHERE comes before GROUP BY. This means WHERE clause filters rows before aggregate calculations are performed. HAVING comes after GROUP BY. This means HAVING clause filters rows after aggregate calculations are performed. So from a performance standpoint, HAVING is slower than WHERE and should be avoided when possible.
3. WHERE and HAVING can be used together in a SELECT query. In this case WHERE clause is applied first to filter individual rows. The rows are then grouped and aggregate calculations are performed, and then the HAVING clause filters the groups.

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[raqibul]

Many Many Thanks For Your Nice Tutorials.Go Ahead.

[dialidasgupta]

Thank you Sir! Your illustration was very clear, and it helped a lot! :)

[DiegoMartinez-tliu]

Thanks for sharing your knowledge. It was helpful to me.

[ians]

Clear and concise! I also like the way you speak! Good job sir! :)

[ceslps]

Good english pronunciation, and very well explained. Thank you my friend.

[krzysztofs]

Thank U Venkat! Very simple video. I see you add some videos missing in the previous sessions. You are the best teacher. Please go on with this tutorial! I watched all your videos. I'm the biggest fan, my career goes further thanks to you.

[Ravivaraavlogs]

Hi venkat sir, can u pls make it one video for execution plan and some tips of performance tunning

[nagireddyveeramreddy]

Hi venkat Sir Please make video on linked servers and performance tuning

[maheshsai]

Since 9 years I have been from IC to the manager and every time I prepare for an interview or to brush my skills, my default search term is kudvenkat SQL

[pawanjoshi]

sir please upload a video of different types of loops used in T-SQL with its real time use.

[ajaypratapyadav]

very nice I learned a lot, request you to please share an query where we can break big files into small pieces, i have required it

[nys]

From Part 10:
where can be uses with select, insert, update, delete
having: only used with select

[rajprasadmishra]

sir plz upload some videos depend on t-sql and tcl commit, rollback and save point

[TheAnkitatri]

Sir plz tell me best practice for this ..

[VinodKumar-cpbt]

Hi venkat In an interview I have been asked to find out the error in this query can you help.
create table employeees(
Firstname varchar2(15) Not null,
Midname varchar2(5),
Lastname varchar2(15) Not null,
SSNnumber char(9),
birthday date,
address varchar2(50),
Sex char(1),
salary int default 800,
superSSN char(9),
depnum numeric(5),
primary key(SSNnumber),
check (Sex == 'M' OR 'F' OR 'm' OR 'f'),
foreign key(depnum) references departments(depnum)
);