Two Sides of the Ledger

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

Domain

SQL

Difficulty

hard

Seniority

L5

Problem

The FinOps team reconciles each region's cloud charges against its budget allocations on a single monthly timeline, where a charge draws the region's balance down and an allocation builds it back up. Charges are stamped with a full billing date while allocations are recorded by month, so line each charge up on its month before combining the two sources. For every region and month, show the net movement and the balance standing after it, earliest month first within each region.

Summary

Two cost tables, one region. Which way does the balance tip?

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