Often I want to categorize by something that isn't a column: person 1: I want to count children/adults/teenagers but there's no column for that! person 2: no problem! jut categorize people based on age! `CASE` is how to write an `if` statement in SQL. Here's the syntax: ``` CASE WHEN THEN WHEN THEN ... ELSE END ``` ## example: Here's how to categorize people into age ranges! ``` SELECT first_name, age, CASE WHEN age < 13 THEN 'child' WHEN age < 20 THEN 'teenager' ELSE 'adult' END AS age_range FROM people ``` (returns first `THEN` where the condition matches) people: | first_name | age | |