alkeshnayak is wrong on that point, as long as you have "< 2 GB" in your database, it will work. However, if you meant: =< "2 GB" then this statement will fail as you cannot use an operator (=<)...

Well first, this is more of an SQL question. But anyway, just do it this way following your syntax:
"SELECT a.dbo.emp.city, b.ado.emp.city FROM a.dbo.emp, b.dbo.emp"
Otherwise think of it this way:...