Returning Buyers

A medium SQL interview practice problem on DataDriven. Write and execute real sql code with instant grading.

Domain

SQL

Difficulty

medium

Seniority

mid, senior

Problem

The retention team needs repeat-buyer signals. Find users who made a second transaction within 1 to 7 days of a previous one, excluding same-day purchases. Return each qualifying user ID once.

Practice This Problem

Solve this SQL problem with real code execution. DataDriven runs your SQL queries against a live PostgreSQL database and grades it instantly.