TOP Enhancements
In SQL Server 2000 and earlier versions, TOP allows you to limit the number of rows returned as a number or a percentage in SELECT queries. As of SQL Server 2005, you can use TOP in DELETE, UPDATE, and INSERT queries and can also specify the number (or percentage) of rows by using variables or any valid numeric returning expression (such as a subquery). The main reason for allowing TOP with DELETE, UPDATE, and INSERT was to replace the SET ROWCOUNT option, which SQL Server traditionally didn’t optimize very well.
You can specify the TOP limit as a literal number or an expression. If you’re using an expression, you must enclose it in parentheses. The expression should be of the bigint data type when you are not using the PERCENT ...
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