Rolling 7-Day System Error Average | Dataford Interview Questions

You are given daily system error logs and asked to calculate a rolling 7-day average of errors for each day in the series. Use PostgreSQL-compatible SQL to return one row per calendar day with the daily error count and the 7-day trailing average, including days with zero errors. Do not use MySQL-only syntax.

Schema

system_errors

Column	Type	Description
error_idPK	INT	Primary key for each error event
occurred_at	TIMESTAMP	Timestamp when the error occurred
system_name	VARCHAR(100)	Name of the system that emitted the error
severity	VARCHAR(20)	Error severity level

Your question is Rolling 7-Day System Error Average. Start with the requirements and the one table in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Schema

system_errors

Column	Type	Description
error_idPK	INT	Primary key for each error event
occurred_at	TIMESTAMP	Timestamp when the error occurred
system_name	VARCHAR(100)	Name of the system that emitted the error
severity	VARCHAR(20)	Error severity level

Your question is Rolling 7-Day System Error Average. Start with the requirements and the one table in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.