Task
Overview of business case:
Handy-Trady Hire (HTH) is a home repair company that employs a number of contractors who specialise in different areas. Contractors have a specialisation in any of the following areas:
Electrical
Cabinet making
Landscaping, plumbing
Driveway sealing
Roof cleaning
Interior & Exterior painting
HTH started as a small family business and for the past five years has been tracking and managing their business activities using an Excel spreadsheet. With view to their expanding business and under the new management, they decided to investigate the option of implementing a database system. Accordingly they hired you to design a relational database to better track and record their operational data.
Your task
Create an ERD for each of the following statements that describe the current business rules for HTH. For each new statement being the business rule, extend the ERD to include the additional business rule in the ERD (created in previous point for example; B will include A&B, C will include A, B & C, etc.)
Use Crows Foot notations and include all of the following in each part:
- All entities with Primary key and any foreign key attributes;
- The relationships between entities;
- The cardinality and optionality of each relationship;
- Any M:N relationships are be resolved to 1:M relationships
HTH discovered business rules/constraints for your ERD:
1. A customer calls HTH to request a home repair job: Details about the customer and the requested job need to be recorded.
2. Each tradesperson specialises in only one trade, and details of their trade and the date acquired need to be kept on record.
3. HTH has a number of trucks (including equipment) and allocates a truck for each tradesperson when hired by HTH. Some tradespersons have their own truck and equipment and advise HTH about this, so in this case they are not assigned a truck.
4. Each team of tradespersons has one supervisor, and a supervisor is to supervise up to 7 tradespersons on the same team.
5. A requested job may require different specialisation depending on the job type - that is a job may require more than one tradesperson to complete.
6. A customer makes a payment for each job by several methods: (by cheque, cash or bank transfer). HTH need to keep a record of payments made by each customer and the method of payment need to be kept.