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| Codd Rules for RDBMS |
The 12 Codd's Rules in relational database management systems (RDBMS) are crucial for ensuring the integrity, consistency, and reliability of database systems. Dr. Edgar F. Codd developed his own set of twelve principles that he believed a database had to follow by in order to be considered a truthful relational database.
Any database system that solely relies on its relational features to handle stored data complies with these principles. This fundamental guideline serves as the basis for all others.
12 EF Codd Rules in RDBMS
Rule 1: Information Rule
In database, information stored in table cell. This
information may be user information or meta data. A database must contain
information in table format.
Rule 2: Guaranteed Access Rule
It is guaranteed that
every piece of data is accessible in logical way. It can be done by using the
name of the table, the primary key and the column name.
Rule 3: Systematic Treatment of NULL Values
A database must treat each Null value consistently and
methodically.
Rule 4: Active Online Catalog Rule
It is necessary to use the same relational database
management system for both storing and accessing the database catalog. A
catalog must contain the complete database's structure description.
Rule 5: The Comprehensive Data Sublanguage Rule
The only way to access a database is through a language with a linear syntax that supports to define, query, and modify data inside the database. Direct use of this language is possible, as well as use through software.
Rule 6: View Updating Rule
The system must be able to update all views that are
theoretically updateable.
Rule 7: High-level Insert, Update, and Delete
A successful data repository must enable high-level
insertions, updates, and deletions so that users can perform these operations
quickly and easily with just one query.
Rule 8: Physical Data Independence
A database's contents must be unaffected by the programs
that use it. Any change to a database's physical layout must not affect how
external applications access the data.
Rule 9: Logical Data Independence
In a database, the logical data must be separate from the
application or user's view. Any modifications to logical data must not have an
impact on the applications that use it.
Rule 10: Integrity Independence
Integrity constraints has to be defined independently of application programs and kept in the catalog. The data system need to automatically enforce them.
Rule 11: Distribution Independence
Users should be unaware of how data is spread among various locations. The distribution should be handled transparently by the data system.
Rule 12: Non-Subversion Rule
The system's interface must not be able to compromise the system's integrity or security if it is granting access to low-level records.
