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Aggregation & Reporting - SQL Practical Query Problems | Aporeon

SQL Practical Query Problems

Aggregation & Reporting

Conditional metrics, duplicate detection, fanout-safe totals, and calendar-aware rolling reports.

4 drillsPractice one at a timeOrdered pathCoding problem

Recommended start

Daily Order KPIs

Builds several daily business metrics in one grouped query while keeping each metric definition explicit.

Medium~25 minStep 1 of 4

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1Daily Order KPIsRecommended startBuilds several daily business metrics in one grouped query while keeping each metric definition explicit.Coding problemMedium~25 minSQLSQL ServerPractice 2

Practice order

4 drillsOne at a time

1Daily Order KPIsUp next / Medium / ~25 min
2Duplicate EmailsEasy / ~15 min
3Avoid Fanout TotalsMedium / ~25 min

Duplicate EmailsGroups normalized email values to identify duplicates before adding or repairing a uniqueness rule.Coding problemEasy~15 minSQLSQL Server

Practice

3Avoid Fanout TotalsPre-aggregates two one-to-many relationships before joining them to prevent fanout from corrupting financial totals.Coding problemMedium~25 minSQLSQL ServerPractice

4Rolling RevenueCombines daily aggregation, a calendar table, and a window frame to calculate true seven-calendar-day revenue.Coding problemHard~35 minSQLSQL ServerPractice

4Rolling Revenue

Hard / ~35 min