Department Cost Totals by Join | Dataford Interview Questions

At Northstar Analytics, finance tracks department spending in a separate expense table. Write a SQL query to join the department and expense data and return the total cost for each department.

Requirements

Join departments and expenses using the department key.
Return each department's name and the sum of its expense cost values.
Group the results by department name.
Order the output by total cost descending, then department name ascending.

Schema

departments

Column	Type	Description
department_idPK	INT	Unique department identifier
department_name	VARCHAR(100)	Department name
region	VARCHAR(50)	Region assigned to the department

expenses

Column	Type	Description
expense_idPK	INT	Unique expense identifier
department_id	INT	Department linked to the expense
expense_type	VARCHAR(50)	Category of expense
cost	DECIMAL(10,2)	Expense amount

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