Monthly Cloud Cost Forecast Error

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

Domain

SQL

Difficulty

hard

Seniority

L4

Problem

We want a naive forecast model for monthly cloud costs. Sum cloud cost amounts at a monthly level. Use the previous month's total as the forecast for the current month, then calculate the absolute percentage error versus actual. Show year-month, actual cost, forecasted cost, and percentage error.

Summary

The forecast was off. By how much?

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