DB Codd Rules

DB Codd Rules

1. Info Rule

   • information which is stored in the db must be a value of some table cell

2. Access Rule

   • Accessible logically with combination of table-name, primary-key and attribute-name

3. NULL Values

   • NULL values in the db must be given a systematic treatment.

4. Active online catalog

   • Structure of db must be stored in an online catalog,

5. View updating rule

   • Views of database must also be updatable by the system.

6. insert, update and delete rule

   • DB must employ support high-level insertion, updation and deletion.

7. Physical data independence

   • App should not have any concern about how the data is physically stored.

8. Logical data independence

   • Logical data must be independent of its user’s view (application).