Entity-Relationship Diagram
The Entity-Relationship Diagram (ERD) shows your database tables, their attributes, and how they relate. Required as a figure in Chapter III.
Entity-Relationship Diagram
What this section does
A figure showing the database tables (entities), their attributes, and the relationships between them. Required as a key figure in Chapter III.
Sample ERD (Sample Bakery Shop)
Drawing rules
| Rule | Why |
|---|---|
| Use crow's-foot notation | Standard, panel-recognised |
| Mark PK and FK | Quick read of which fields link tables |
| Show cardinality | Avoids debate at defense |
| Resolve N..N with join table | ORDER_ITEM is the example |
| Match the live database | Inconsistency = panel question |
Tools
| Tool | Notes |
|---|---|
| draw.io | Free, ERD shape set built in |
| DBDiagram.io | Generates from a text spec |
| MySQL Workbench | Reverse-engineers from live DB |
| Lucidchart | Collaborative, paid |
Caption + prose
Figure 3.4 shows the entity-relationship diagram of the proposed database. The CUSTOMER entity has a one-to-many relationship with ORDER. Each order has multiple ORDER_ITEMs, each of which references a PRODUCT. The USER and INVENTORY_LOG entities track who changed inventory, when, and why - supporting the audit feature described in Chapter IV.
Panel defense checklist
- [ ] All entities the system reads or writes are present.
- [ ] Primary and foreign keys are marked.
- [ ] Cardinality is shown for every relationship.
- [ ] No N..N relationships without a join table.
- [ ] Every entity has at least one attribute besides id.
- [ ] Diagram references the database in your live system.
- [ ] Caption: 'Figure 3.4. Entity-Relationship Diagram.'
Mentor’s tip: Crow-foot notation. Mark PKs and FKs. Resolve N..N with join tables. The diagram must match the actual database the panel will see in Chapter IV. Caption Figure 3.4.
Discussion
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