Get to know tables
OVER()
Computations with OVER()
Aggregate functions with OVER()
10. Practice 1
OVER() and WHERE
Summary

## Instruction

Nice! The concept of pure OVER() might seem easy, but let's do a few more questions to be on the safe side before we move on to more complex things.

## Exercise

For each purchase with department_id = 3, show its:

• id,
• department_id,
• item,
• price,
• maximum price from all purchases in this department,
• the difference between the maximum price and the price.

### Stuck? Here's a hint!

Use MAX(price) OVER() - price to calculate the difference.