it should be if you're using sql server
SELECT c.CompanyName,SUM( UnitPrice * Quantity ) AS TotalIncome
FROM customers c
JOIN sales s
ON s.CustomerID = c.CustomerID
INNER JOIN Time t
ON t.TimeID = s.TimeID
WHERE t.Year= '2012'--put your year value here
GROUP BY c.CompanyName
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SQL Server MVP
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