Hi, these are excerpts from a Database Systems past paper, our lecturer did not provide solutions, so I don't know if I'm right or not.

I would appreciate solutions.

4. (a) Briefly explain what a Trigger is. The following relations form part of a relational database (the relations are self-explanatory) (b) Balance) CUSTOMER(Cust#, ORDER(Order#, Date, Cust#) ORDERLINE(Order#, Part#, Amount-Ordered) PART (Part, Desc, Stock, Item-Class, Unit-Price) CNane , CAddress, Cton , With reference to this relational schema, write SQL state ments for the following queries: i. List the name of the customer who has placed Order (4 123 (i.e. Order have ordered Part 456 (i.e. Part# at least 3 parts and the amount ordered for each part 123) ii. List the names of customers who are in Cardiff and 456). 4 iii. List the order numbers (Orders) for orders that contain 4 is at least 10 iv. List the description (Desc) of those parts for which the is greater than the amoun amount ordered average ordered for Part 456 (Part#-456) in Order 123 Order# 123) 4]