What are the Codd’s Rules?

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• What are the Codds Rules?

What are the Codds 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.
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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
customers. Users can use the same query
terminology to connect to the collection which
they use to connect to the information source
itself.
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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
by the program.
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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 any
effect on how the information is being utilized
by external programs.
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Rule 9 Sensible Data Independence The logical
information in a knowledge source must be
separate of its users 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 can be
individually customized without the need of any
alternation in the program. This concept makes a
knowledge source in addition to the front-end
program and its customer interface.
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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 restrictions.
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