Top Error Codes by Drive | Dataford Interview Questions

Foundation Robotics needs a report of the most frequent error codes generated by each robotic drive category during the 30-day period ending on 2026-09-14. Write a SQL query to produce this report.

Output

One row per qualifying category and error code, with columns category_name, error_code, and error_count.
Include only known categories, non-null error codes, and events from 2026-08-16 through 2026-09-14 inclusive.
Return at most the three most frequent error codes per category. Break frequency ties by ascending error_code.
Sort by category_name ascending, then error_count descending, then error_code ascending.

Schema

robotic_drive_categories

Column	Type	Description
category_idPK	INT	Unique robotic drive category identifier
category_name	VARCHAR(80)	Name of the robotic drive category

robotic_drive_error_events

Column	Type	Description
event_idPK	INT	Unique error event identifier
category_id	INT	Referenced robotic drive category
error_code	VARCHAR(20)	Generated robotic drive error code
occurred_at	DATE	Date on which the error occurred

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