SQL for Funnel Segments | Dataford Interview Questions

Write a query to identify top-performing user segments based on multi-step conversion funnels.

Calculate performance for the funnel viewed_offer → started_application → completed_application. A user counts as started only when the start occurs after the view, and counts as completed only when completion occurs after the start. Include every segment, including segments with no qualifying starters.

Output

One row per segment with segment, started_users, completed_users, conversion_rate, and performance_rank.
conversion_rate is the completed-user percentage among qualifying starters, with zero for segments without starters.
Sort by rank ascending, then segment alphabetically, with NULL segments last.

Schema

users

Column	Type	Description
user_idPK	INT	Unique user identifier
segment	VARCHAR(50)	User segment label

funnel_events

Column	Type	Description
event_idPK	INT	Unique event identifier
user_id	INT	User associated with the event
event_name	VARCHAR(40)	Funnel event type
event_at	TIMESTAMP	Timestamp when the event occurred

Your question is SQL for Funnel Segments. Start with the requirements and the two tables in the Question tab.

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Problem