Back to Practice
#0370
Churned Users With No Recent Event
MediumSQL24 min20 XP
Problem
Return user_id values whose latest event_date is before 2026-02-01.
Why This Matters
SQL interviews usually test whether you can turn a business question into the right rows, grouping level, join type, and edge-case behavior.
Schema
events(user_id INTEGER, event_date TEXT)
Examples
Example 1
Inputusers 1 and 3 last active in January
Output1 and 3
MAX(event_date) gives each user’s latest activity date.
Constraints
- Return only the requested columns.
- Use deterministic ORDER BY when multiple rows are returned.
- Assume SQLite-compatible SQL unless the prompt states otherwise.
CodeSQL
Visible browser tests run here when available.
Testcases1 visible / 3 hidden categories
Core SQL case
Inputusers 1 and 3 last active in January
Expected[[1],[3]]
MAX(event_date) gives each user’s latest activity date.
Hidden Test Categories
Empty or missing matchesDuplicate rows or tiesNULL values where the pattern commonly breaks