1. A view is defined using the create view command:

create view v as <query expression>
where <query expression> is any legal query expression. The view created is given the name v.

2. To create a view all_customer of all branches and their customers:

create view all_customer as

â…¡bname,cname(deposit) ∪â…¡bname,cname(borrow)

3. Having defined a view, we can now use it to refer to the virtual relation it creates. View names can appear anywhere a relation name can.

4. We can now find all customers of the SFU branch by writing

â…¡cname(∑bname="SFU"(all customer))