SQL Window Functions: Explained (with examples)

Window functions in SQL are a very helpful feature if you want to perform calculations on your data.

But they can be a little tricky to understand.

In this video, you’ll learn what a window function is, why you would use one, and see a couple of examples on an SQL database.

This functionality is available in Oracle, SQL Server, MySQL, and Postgres.

Timestamps:
00:00 What is a window function?
00:47 The sample data and running total
01:39 Window function syntax explained
02:45 Demo of SQL with a running total
05:22 The partition concept
06:25 Adding a “partition by” clause to our query
08:02 Other scenarios for window functions

Links:

[eminjs]

First of all, thanks for clarification. Second, just to warn some people like me who could potentially be stumped by a little typo: in 6:09, in the presentation, write to the order_id 5 the date also 2022--04-03, and not 2022-03-03, otherwise we would not have a logical grouping. Again, I want to than you again Ben: only after watching this video I truly feel that I grasp the window functions completely. Kudos to your amazing clarification skills.

[andresil]

Thanks, Ben! You nailed in the explanation and can show things in a very clear way.

[osoriomatucurane]

Another Awesome tutorial, crystal clear and concise by the SQL Master! This man is truly a legend! After numerous tutorial, I finally got my head arround the order by argument in the over ( ) clause. Thank you a lot. This is the relative sorting against or over the particular group/window.

[alaeeddinehajji]

you have the best SQL playlist, Thank you

[Port]

You have done great when it comes to good video creation and Knowledge delivery. Nice! Learned what I needed. Nice!

[huffypuff]

This is honestly such an amazing video. Thank you so much.

[shirtless]

Great teacher!!! One of the best I have seen.

[samplayingkeeps]

Thank you so much for this. It was very clear and helpful.

[nataliataranova]

Clear & informative tutorial, thank you!

[cindystokes]

When adding the partition, I accidentally did not grab the "order by" for the outer query and it worked perfectly. So rather than add additional code to make it work, makes more sense to let it run with less code? Discovered this completely by accident. Here is the code.

Select order_id,
order_date,
order_total,
SUM(order_total) OVER (
PARTITION BY order_date
ORDER BY order_id ASC
) AS running_total
From orders

[mauroldanr]

Are te windows function good for performance compared to other options retriving same results?

[hintsoftware]

Can we use where clause or any kind of filters in any way for each windows function seperately ?
We are unable to fully utilize window function without where clauses... or any trick to do so in sql server ?

[A_View_From_The_Shire]

Could you not achieve the same results using a GROUP BY clause?

[hasanmougharbel]

Hey man, glad to meet again.
I have only a simple enquiry as a new sql learner.
How order by clause differs from rank function in sql?
Thanks for taking care of this.

[ziad]

I like the video and the channel content looks cool => subscribed

[pging]

appreciate the video - but you're introducing concepts a little too quickly here - namely the frame -- the default frame - unbounded preceding to the current row - and this is a little too tricky for people to grasp without a direct explanation - the running total would make sense in light of the default frame.