Chapter 3

GIGO

Data Control

1. Data validation (rules, reasonable check)

   - presence check

   - range check (e.g. age, month)

   - format check

   - check digit (HKID, ISBN)

2. Data verification (inputted data, source)

   - confirmation

   - input data twice (e.g. password)

Chapter 3:

Data Validation

Demon

Data verification