Session Ready
Exercise

GROUP BY practice

As you've just seen, combining aggregate functions with GROUP BY can yield some powerful results!

A word of warning: SQL will return an error if you try to SELECT a field that is not in your GROUP BY clause without using it to calculate some kind of value about the entire group.

Note that you can combine GROUP BY with ORDER BY to group your results, calculate something about them, and then order your results. For example,

SELECT sex, count(*)
FROM employees
GROUP BY sex
ORDER BY count DESC;

might return something like

sex count
female 19
male 15


because there are more females at our company than males. Note also that ORDER BY always goes after GROUP BY. Let's try some exercises!

Instructions 1/4
undefined XP
  • 1

    Get the release year and count of films released in each year.

  • 2

    Get the release year and average duration of all films, grouped by release year.

  • 3

    Get the release year and largest budget for all films, grouped by release year.

  • 4

    Get the IMDB score and count of film reviews grouped by IMDB score in the reviews table.

Loading