Practice eBay SQL Question | Real Coding Interviews

Quick Summary

Count per-user transactions within a 31-day window starting from a coupon issue date.
Classify recipients into three activity tiers based on transaction counts.
Preserve all coupon recipients, including those with zero qualifying transactions.

What This Tests

Date range filtering with inclusive boundaries
Preserving primary entities during relational joins
Conditional aggregation and classification logic
Handling sparse datasets without dropping unmatched rows

Common Patterns

Left Join

Date Arithmetic

Aggregation

Groupby

Table: Users

+-------------+------+
| Column Name | Type |
+-------------+------+
| user_id     | int  |
| coupon_date | date |
+-------------+------+
user_id is the primary key unless the input contains event-level duplicates.

Table: Transactions

+------------------+-------+
| Column Name      | Type  |
+------------------+-------+
| transaction_id   | int   |
| user_id          | int   |
| transaction_date | date  |
| amount           | float |
+------------------+-------+

transaction_id is the primary key unless the input contains event-level duplicates.

Test Cases

Input

Output

Expected