Пример из хелпа команды UPDATE
C. Using the UPDATE statement with information from another table
The following example modifies the SalesYTD column in the SalesPerson table to reflect the most recent sales recorded in the SalesOrderHeader table.
USE AdventureWorks;
GO
UPDATE Sales.SalesPerson
SET SalesYTD = SalesYTD + SubTotal
FROM Sales.SalesPerson AS sp
JOIN Sales.SalesOrderHeader AS so
ON sp.SalesPersonID = so.SalesPersonID
AND so.OrderDate = (SELECT MAX(OrderDate)
FROM Sales.SalesOrderHeader
WHERE SalesPersonID =
sp.SalesPersonID);
GO