When running a referral program, it’s important to understandwho already shares your app, an who are those power users? Because who knows, maybe there’re more.
In this exercise, let’s find out the user ID of the most powerful referral user (a user who invited the most users).
referrer_id column inside the
users table contains a value of another user ID (ID of a user whose referral link was used). That user ID (inside the
referrer_id column) is exactly the user ID we need to solve the exercise.