multitier asp.net

Hi wondering if anyone can help me with this..

I have read loads of articles regarding mutli tier development in asp.net and I understand the idea is that you split the presentation layer, datalayer and business layer so if you change one, it shouldn't break the other. I have seen numerous solutions which the buiness layer will return a dataset back to the gui and they will bind this striaght to the datagrid. This is all good, but this means the grid is binding to fields in the database and if you change the db, you will break the datagrid binding. How do people get around this ? or is it common practice. I know this is more of an architecture question but I have read a good few articles on the asp.net side and was looking for some help...

many thanks
Mox.