Employee - Asset (1- many Relationship)

1. Relationship rules

Each employee can be assigned some of the companies assets for their use. This can include things like a company Computer, mobile device, car.

1. Employees can be allocated 0, 1 or many Assets for their use.

2. Each Asset must be allocated 1 Employee. (This means that the Employee MUST be created before the Asset, so in the case of a "corporate" Asset it would probably be assigned to a technician).

(Notice the use of 0,1 or many, or 0 or 1. This makes it very clear what the relationship is).

2. Entity Relationship Diagram (ERD)

Based on the relationship rules we can create an ERD that shows how the entities are related.

1. Draw the entities and show how they are linked ( In this case there are only 2 tables so there is an obvious line between them )

2. Add cardinality constraints (1-many, etc.). In the following diagram I have shown each rule separately then the combined diagram which is the Entity Relationship Diagram (ERD).

3. Fully attributed ERD (Extended/ Enhanced ERD)

To develop an entended ERD

1. Put attributes to each of the entities. What makes up the entity?

2. Identify the Primary Keys [PK] and Foreign Keys [FK].

3. Resolve any many-many relationships

This is a 1-many relationship so you don't need to add any additional "joining" tables.

Activity

Add some data to the Asset Table. You can use the following test data.

Notes

• In the sample following a partial view of the Employee table is showing to illustrate the EmpID Key field attribute.

• If you allocate an Employee to an Asset, The Employee ID (EmpID) must exist in the Employee table.

• An Asset must have an Employee allocated.

• Employees can have 0 (Bloggs),1 (White) or many (Zen) Assets allocated.