a) Create the following roles: user, manager, owner. Grant all privileges to owner, read privileges to user, and insert privileges to manager.

b) Create a new role: trainee. Grant privileges only to columns orderdate and shippeddate to trainee and set the role valid until 30.5.2022.
c) Create a function get_shipping_info(varchar) that returns a table. The table should have the following columns shipname, shipaddress, shipcity, shipcountry. The function should return orders where the shipname matches the given string.
d) Extend the function in c) so that it accepts three parameters: get_shipping_info(varchar, timestamp, money). The function should return orders where the shipname matches the given string, orderdate is equal or earlier than the given timestamp and finally, freight cost is +-10€ from the given money.