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.
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.
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.
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.
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 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.
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. You can join the dba institute with the oracle course to make your career in this field.
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