Question

How to get top n rows from a table where value of n is passed at run-time?

Answer 1

In SQL Server 2005 and beyond you can actually parameterise the top command.

The code below is from MSDN

USE AdventureWorks;
GO
DECLARE @p AS int;
SELECT @p=10
SELECT TOP(@p)*
FROM HumanResources.Employee;
GO

In earlier versions of SQL Server you will need to either use rowcount or dynamic sql.