SQL for Underperforming Shifts | Dataford Interview Questions

How would you write a query to identify the top 10% of underperforming shifts in a given month?

Use the shifts and shift_targets tables. For this exercise, underperformance is measured by the lowest actual-to-target percentage. Include only shifts in February 2025 with non-null actual units and positive targets.

Output

One row per selected shift with the columns shift_id, store_id, shift_date, shift_name, actual_units, target_units, and performance_pct
Include the lowest 10% of eligible shifts, rounding the required count up
Order by underperformance, then shift date and shift ID for ties

Schema

shifts

Column	Type	Description
shift_idPK	INT	Unique shift identifier
store_id	INT	Store associated with the shift
shift_date	DATE	Calendar date of the shift
shift_name	VARCHAR(30)	Shift label
actual_units	INT	Units processed during the shift

shift_targets

Column	Type	Description
target_idPK	INT	Unique target record identifier
shift_id	INT	Referenced shift identifier
target_units	INT	Target units for the shift

Your question is SQL for Underperforming Shifts. Start with the requirements and the two tables in the Question tab.

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Problem