sql code in aspx page

hi all, 
i was reading few best practices documents on devloping applicaitons and learned that it is not a good practice to use sql code in aspx page. my quesiton is, if we use a control such a grid view for example, we need to specify a data source and select, update an delete statements. where shoudl i specify the select/update/delete statemtns if it is not a good practice to use sql code in aspx? i am specifying a stored procedure for select, update and delete statments in the apsx page. is this not a good practice?
thanks for any thoughts.