First Normal Form (1NF)

Definition

A relation is in 1NF if:

• All attributes contain atomic values (indivisible)

• No repeating groups or arrays

• Each tuple is unique

Example - Violating 1NF

CopyEmployee Table (Violates 1NF):
┌────────────┬────────┬────────────┬───────────────┐
│ EmployeeID │  Name  │ Department │ Phone Numbers │
├────────────┼────────┼────────────┼───────────────┤
│    101     │ Alice  │   Sales    │ 12345, 67890  │
│    102     │  Bob   │    IT      │     54321     │
│    103     │ Carol  │    HR      │ 98765, 43210  │
└────────────┴────────┴────────────┴───────────────┘

Problem: Phone Numbers column contains multiple values.

Converting to 1NF

CopyEmployee Table (1NF):
┌────────────┬────────┬────────────┬─────────────┐
│ EmployeeID │  Name  │ Department │ PhoneNumber │
├────────────┼────────┼────────────┼─────────────┤
│    101     │ Alice  │   Sales    │    12345    │
│    101     │ Alice  │   Sales    │    67890    │
│    102     │  Bob   │    IT      │    54321    │
│    103     │ Carol  │    HR      │    98765    │
│    103     │ Carol  │    HR      │    43210    │
└────────────┴────────┴────────────┴─────────────┘