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Running Moving Average per System

MediumSQL · PostgreSQL00:00
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Your question is Running Moving Average per System. Start with the requirements and the two tables on the right.

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Problem

Write a query using SQL window functions to calculate a running 30-day moving average of user activity per system.

Use activity_logs to calculate daily activity as the total of activity_units. Treat NULL activity units as zero. The 30-day period includes the current activity date and the preceding 29 calendar days.

Output

  1. One row per system and date with activity records.
  2. Columns: system_name, activity_date, daily_activity, and moving_30_day_avg.
  3. Order by system_name, then activity_date ascending.

Schema

systems
ColumnTypeDescription
system_idPKINTUnique system identifier
system_nameVARCHAR(100)System display name
classificationVARCHAR(30)System classification
activity_logs
ColumnTypeDescription
activity_idPKINTUnique activity record identifier
user_idINTIdentifier of the user generating activity
system_idINTSystem associated with the activity
activity_dateDATECalendar date of the activity
activity_unitsINTNumber of activity units recorded
Tablessystemsactivity_logs
Your solutionPostgreSQL
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