Whenever you want to execute a sql statement that shouldn't return a value or a record set the ExecuteNonQuery should be used. So if you want to run an update, delete, or insert statement, you should use the ExecuteNonQuery. ExecuteNonQuery returns the number of rows affected by the statement.

This sounds very nice, but whenever you use the SQL Server 2005 IDE or Visual Studio to create a Stored Procedure it adds a small line that ruins everything. That line is: SET NOCOUNT ON; This line turns on the NOCOUNT feature of SQL Server, which "Stops the message indicating the number of rows affected by a Transact-SQL statement from being returned as part of the results" and therefore it makes the SP always to return -1 when called from the application (in my case a web app).

In conclusion, remove that line from your SP and you will now get a value indicating the number of rows affected by the statement.