What is entity-relationship modeling and normalization?

Question

Accepted Answer

**ER Modeling** — identifying entities, attributes, relationships. **Normalization** — reducing redundancy.

**ER Modeling Steps:**
1. Identify entities (Customer, Order, Product).
2. Define attributes for each entity.
3. Identify relationships (1:1, 1:M, M:N).
4. Define cardinality and participation.

**Normalization Forms:**
```
1NF: No repeating groups, atomic values
2NF: 1NF + no partial dependencies
3NF: 2NF + no transitive dependencies
BCNF: Every determinant is a candidate key
```

**Example (3NF):**
```
Before: Orders(order_id, customer_name, customer_city, product, price)
After:
  Orders(order_id, customer_id, product_id, quantity)
  Customers(customer_id, name, city)
  Products(product_id, name, price)
```

**Benefits:** Data integrity, reduced redundancy, easier maintenance.

Systems Analyst: What is entity-relationship modeling and normalization?