SQL practice: SELECT: Choosing Columns

Show only customer_name and city from customers.

Show every column of branches.

List every different region in branches.

Show employee_name under the heading staff, and salary under monthly_pay.

For every product, show its name and its profit per unit (unit_price minus cost_price), with the calculated column named profit.

List every unique combination of city and customer_type in customers.

Show each product's name and what its price would be after a 10% discount, named sale_price.

How many different role values exist in employees? (Get the list — counting comes in Chapter 9.)