Practice Window Functions (19.1.3) - Advanced SQL and NoSQL for Data Science

Practice: Window Functions

Lesson 19.1.3Advanced SQL and NoSQL for Data Science

Practise this section

9 questions

Flashcard drill
2 cards from this section. Quick, good the night before a test.
Exercise
6 questions · about 4 min · pass mark 70%. Hints available.
Sign up to start the exercise
Quiz
3 questions · about 2 min · pass mark 70%. Hints available.
Sign up to start the quiz

6 sample questions

Question 1.
What does the ROW_NUMBER() function do?
Show hintHide hint
Think about how you would number items in a list.
Question 2.
Explain what a window function is.
Show hintHide hint
It's about looking at groups of rows.
3Question 3.
What is a primary feature of window functions?
- They aggregate data
- They perform calculations without collapsing output
- They join tables
Show hintHide hint
Remember how aggregation would work differently!
4Question 4.
True or False: The RANK() function can assign the same rank to multiple rows if their values are equal.
- True
- False
Show hintHide hint
Think about how ranking works in a competition.
Question 5.
Create a SQL statement that retrieves employee names and their salaries, ranked within their departments, using the RANK() function. How would you ensure departments with no employees are included?
Show hintHide hint
Consider how joins and window functions work together.
Question 6.
Analyze a dataset of sales over the last year. Write a query using LAG() to find out the month-over-month percentage change in sales.
Show hintHide hint
Think about how to calculate the difference over time.

5 more questions in this section. Enroll free to practise them all.