Then and Now

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

Domain

SQL

Difficulty

hard

Seniority

L5

Problem

We track every model version with the accuracy it scored and the time it was trained, and a version only counts when both of those are recorded. For each model, report its average accuracy across all counted versions, the accuracy of its most recent version, and the gap between that latest accuracy and the average of its earlier versions, everything rounded to two decimals. A model with only one counted version has no earlier versions, so its gap is 0.

Summary

Accuracy used to be higher.

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