Question:

Describe briefly the three parts of the Relational Model.

(a) The term integrity refers to the accuracy or correctness of the data in the database. Define the following terms:

i) Domain Integrity
ii) Entity Integrity
iii) Referential Integrity

(b) Given the following business rules for a situation:

1. Each vendor can supply many parts to any number of warehouses, but need not supply any parts. The identifier for vendor is vendor_id and other attributes includes: vendor_name, address, tel. The identifier for part is part_no other attributes includes: part_desc, QOH and Unit Price. The identifier for Warehouse is warehouse_no and other attributes include location.

2. Each Part can be supplied by any number of vendors to more than one warehouse, but each part must be supplied by at least one vendor to a warehouse.

3. Each warehouse can be supplied with any number of parts from more than one vendor, but each warehouse must be supplied with at least one part.

4. The attribute for the supplies relationship are: shipping mode and unit_cost.

(i) Draw an ERD from the above scenario. You have to include the minimum and maximum cardinalities and also show whether it is an optional or mandatory relationship from the above scenario.

(ii) Convert the above ERD into its relevant Relational Schema.