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#0390

Refund Adjusted Revenue

MediumSQL24 min20 XP

Problem

Return net_revenue as total order amount minus total refunded amount.

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

orders(order_id INTEGER, amount INTEGER); refunds(refund_id INTEGER, order_id INTEGER, amount INTEGER)

Examples

Example 1
Input150 gross revenue and 20 refunded
Output130

COALESCE protects the subtraction when there are no refunds.

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
Input150 gross revenue and 20 refunded
Expected[[130]]

COALESCE protects the subtraction when there are no refunds.

Hidden Test Categories
Empty or missing matchesDuplicate rows or tiesNULL values where the pattern commonly breaks