Consider the following schema:
Suppliers(sid: integer, sname: string, address: string)
Parts(pid: integer, pname: string, color: string)
Catalog(sid: integer, pid: integer, cost: float)
The Catalog relation lists the prices charged for parts by Suppliers.
For each of the following transactions, state the SQL isolation level that you would use and explain why you chose it.
1. A transaction that adds a new part to a supplier’s catalog.
2. A transaction that increases the price that a supplier charges for a part.
3. A transaction that determines the total number of items for a given supplier.
4. A transaction that shows, for each part, the supplier that supplies the part at the lowest price.