What is the difference between GROUP BY and window functions in SQL?

What is the difference between GROUP BY and window functions in SQL?

GROUP BY aggregates data across rows, while window functions perform calculations across a set of rows related to the current row.

Can you give me an example of each?

Sure! For GROUP BY, you might use it to count the number of orders per customer. For window functions, you could calculate a running total of sales.

When should I use one over the other?

Use GROUP BY when you need aggregated results, and window functions when you need to retain individual row details while performing calculations.

Are there performance differences between them?

Yes, GROUP BY can be more efficient for large datasets when you only need aggregated results, while window functions can be slower due to their complexity.