как насчет
SELECT @variableOne = avg(someColumn), @variableTwo = avg(otherColumn) from tblTable
это работает на меня очень хорошо.
Limited users don't normally have write access to folders that are common to all users. Are you sure you don't mean to write to a different folder instead?
For example, you could use Environment.SpecialFolder.ApplicationData
(current user, roaming data) or Environment.SpecialFolder.LocalApplicationData
(current user, non-roaming data).