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#0384
Users With No Purchases After Signup
MediumSQL24 min20 XP
Problem
Return user_id values for users with no purchase on or after their signup_date.
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
users(user_id INTEGER, signup_date TEXT); purchases(user_id INTEGER, purchase_date TEXT)
Examples
Example 1
Inputuser 2 purchased before signup only; user 3 never purchased
Output2 and 3
The date condition belongs in the JOIN so unmatched users survive.
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
Inputuser 2 purchased before signup only; user 3 never purchased
Expected[[2],[3]]
The date condition belongs in the JOIN so unmatched users survive.
Hidden Test Categories
Empty or missing matchesDuplicate rows or tiesNULL values where the pattern commonly breaks