SQL for Monthly Cost Centers | Dataford Interview Questions

Write a SQL query to analyze monthly operational costs by department and identify the top three cost centers each month.

Use the provided operational cost, cost center, and department data. Include only cost centers associated with a department and treat missing cost amounts as zero.

Output

One row per selected cost center and month.
Columns: cost_month, department_name, cost_center_name, monthly_cost, and monthly_rank.
Include the three highest-cost centers for each month, ordered by month and monthly rank. Break equal-cost ties by ascending cost center ID.

Schema

departments

Column	Type	Description
department_idPK	INT	Unique department identifier
department_name	VARCHAR(100)	Department name

cost_centers

Column	Type	Description
cost_center_idPK	INT	Unique cost center identifier
cost_center_name	VARCHAR(120)	Cost center name
department_id	INT	Department associated with the cost center

operational_costs

Column	Type	Description
cost_idPK	INT	Unique operational cost identifier
cost_center_id	INT	Cost center charged for the expense
cost_date	DATE	Date the cost was recorded
cost_amount	DECIMAL(12,2)	Operational cost amount

Your question is SQL for Monthly Cost Centers. Start with the requirements and the three tables 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