These guidelines can be applied on information source program that manages saved information using only its relational abilities. This is a basis concept, which acts as a base for all the other guidelines.

1. What are the Codd’s Rules?
What are the Codd’s Rules?
These guidelines can be applied on information source program that
manages saved information using only its relational abilities. This is a
basis concept, which acts as a base for all the other guidelines.
Rule 1: Information Rule
The information saved in a knowledge base, may it be customer
information or meta-data, must be a value of some desk cell. Everything
in a knowledge base must be saved in a desk format.
Rule 2: Assured Accessibility Rule
Every individual information element (value) is going to be accessible
rationally with a combination of table-name, primary-key (row value), and
attribute-name (column value). No other indicates, such as pointers, can
be used to get access information.

2. Rule 3: Methodical Therapy of NULL Values
The NULL principles in a knowledge source must
be given a thorough and uniform treatment. This is
a very important concept because a NULL can be
considered as one the following − information is
missing, information is not known, or information
is not applicable.
Rule 4: Active On the internet Catalog
The framework description of the entire
information source must be saved in an internet
based collection, known as information
vocabulary, which can be utilized by authorized

3. Rule 5: Comprehensive Data Sub-Language Rule
A data base can only be utilized using a
terminology having straight line format that
supports information definition, information
adjustment, and transaction management
functions. This terminology can be used directly or
through some program. If the information source
allows access information without any help of this
terminology, then it is considered as a violation.
Rule 6: Perspective Upgrading Rule
All the views of a knowledge source, which can
hypothetically be updated, must also be updatable

4. Rule 7: High-Level Insert, Update, and Remove
Rule
An information source must assistance high-level
placement, updation, and removal. This must not
be limited to a individual row, that is, it must also
assistance union, junction and less functions to
generate sets of information information.
Rule 8: Actual Data Independence
The information saved in a knowledge source
must be in addition to the programs that connect
to the information source. Any alternation in the
physique of a knowledge source must not have

5. Rule 9: Sensible Data Independence
The logical information in a knowledge source
must be separate of its user’s view (application).
Any alternation in logical information must not
affect the programs using it. For example, if two
platforms are combined or one is split into two
different platforms, there should be no effect or
modify on the consumer program. This is one of
the most difficult concept to apply.
Rule 10: Reliability Independence
An information source must be in addition to the
program that uses it. All its integrity restrictions

6. Rule 11: Submission Independence
The end-user must not be able to see that the
information is allocated over various locations.
Users should always get the impression that the
information is located at one site only. This
concept has been regarded as the basis of
allocated information source systems.
Rule 12: Non-Subversion Rule
If a program has an customer interface that
provides access low-level information, then the
consumer interface must not be able to subvert
the program and bypass security and integrity