The following SQL Sever T-SQL samples demonstrates the usage of SET ROWCOUNT and TOP to put a cap on updates:

-- T-SQL limiting the number of UPDATEs

USE tempdb;

SELECT EmployeeId = CONVERT(INT,EmployeeID), ManagerID

INTO Employee

FROM AdventureWorks.HumanResources.Employee

GO

-- (290 row(s) affected)

UPDATE TOP (5) Employee

SET ManagerID = 109

GO

-- (5 row(s) affected)

SET ROWCOUNT 7

UPDATE Employee

SET ManagerID = 100

SET ROWCOUNT 0

GO

-- (7 row(s) affected)

DROP TABLE Employee