Write a query to show department salary share using SUM OVER.

Short answer: Compute each employee’s salary share within department via Salary / SUM(Salary) OVER (PARTITION BY DepartmentId).

Sample solution

SELECT EmpId, DepartmentId, Salary,
       CAST(100.0 * Salary / SUM(Salary) OVER (PARTITION BY DepartmentId) AS DECIMAL(5,2)) AS DeptPct
FROM Employees;

Window aggregates keep detail rows — unlike GROUP BY alone.