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The Referral Loop

Mission brief

Challenge Briefing

Hard

Recursive CTEs
Hierarchical Queries
Paths

A marketing promo went viral! Your task is to find the "Top Influencer"—the original user (root) who started a referral chain that reached at least 5 levels deep. A "Top Influencer" is a user who was NOT referred by anyone else, making them the ultimate source of the chain.

The Referral Loop

Find the "Top Influencer" who started a chain of at least 5 levels of referrals.

The Narrative

Schema Diagram

referrals

user_idINT

referrer_idINT

Challenge a Friend

One SQL table. One SQL condition.
Still tricky for most developers.

SQL Editor

Terminal Output

Initializing Database Engine v1.8.0...

Write a SQL query, then click Run Query

Keep practicing

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