Que :- Discuss concepts of RDBMS with Codde Rule ?
1) Information Rule :-
This rule is about the storing the information Dr. E.F codde suggest that information storage in relational data model in the form of relation where relation as treated as table with in intersection of row and column where each row represent one record and where each column represent field create a record it create database.
2) Granted access Rule:-
This rule about the accessing of data in each relation Dr. E.F Codde suggest that every piece of information in a relation is uniquely access with any ambiguity (with out any confusion) after getting this rule all RDBMS package suggest a concept of primary key it is that field in table that never be duplicate and that never be NULL.using this field we can access all other field within a relation uniquely there is only one primary key in each relation.
3) Systematic Treatment of Null value :-
During collecting information about entity many of the information is missing for ex:-if we collect information about any employee i,e newly join in an organisation then all his information feed in employee relation but till now his department is not decided now question is that what is the value of Department field,some people suggest about this situation that is if field type is character put space,if field type is numeric put zero (0) but Dr. E.F codde suggest that put NULL in missing information .
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Discuss 12th Rule of Coddes?
Any RDBMS package is bashed on coddes rule. Dr E.F codde is a mathematician that provide 12th rule of Relational Data Model. These are follow :-
1) Information Rule
2) Granted access Rule
3) Systematic Treatment of Null value
4) Active Online Catalog Based on relational principle
5) View Updating Rule
6) Integrity Independence Rule
7) Relational Manipulation Rule
8) Physical Data In dependency
9) Logical Data in dependency
10) High Level Insert, Delete and update
11) Non-sub version Rule
12) Distribution Independence
1) Information Rule :-
This rule is about the storing the information Dr. E.F codde suggest that information storage in relational data model in the form of relation where relation as treated as table with in intersection of row and column where each row represent one record and where each column represent field create a record it create database.
If we want to store information about any course then we have to create a relation with required number of attributes (Field) in any RDBMS package.
2) Granted access Rule:-
This rule about the accessing of data in each relation Dr. E.F Codde suggest that every piece of information in a relation is uniquely access with any ambiguity (with out any confusion) after getting this rule all RDBMS package suggest a concept of primary key it is that field in table that never be duplicate and that never be NULL.using this field we can access all other field within a relation uniquely there is only one primary key in each relation.
This concept is given functional dependency where another attribute of a relation is dependent on primary key of that relation.
3) Systematic Treatment of Null value :-
During collecting information about entity many of the information is missing for ex:-if we collect information about any employee i,e newly join in an organisation then all his information feed in employee relation but till now his department is not decided now question is that what is the value of Department field,some people suggest about this situation that is if field type is character put space,if field type is numeric put zero (0) but Dr. E.F codde suggest that put NULL in missing information .
4) Active Online Catalog Based on relational principle :-
Dr. E.F codde suggest that there must be a provision to store data about data means if we want to create any data in relation database like tupple , processor, view etc then all RDBMS package store information about this object i.e on which date is create and time is created whose reader of that object on which time which is created. storing data about data should be in the form of relation it should be or created automatically.
5) View Updating Rule :-
This rule about the user view if we create any view for any user then it should be up datable.each user required different amount of data for this purpose codde`s suggest that RDBMS package should has a provision to create a view for different user.
This rule about the integrity about of database if any integrity (rule) is impose on any attributes then the maintains of this integrity should be independence from data.
i.e as follow :-
select, projection, Division, Cartesian product, join, set different, union, intersection etc.
8) Physical Data Independency :-
This rule about the data independency it suggest that physical data of a database should independence from logical data.
9) Logical Data in dependency :-
This rule about the maintaining of logical data independence from the external data.
10) High Level Insert, Delete and update :-
This rule is about the interface to performing operation with any RDBMS generally we perform three operations i.e insert,delete and update.this three operation can be perfome sucessfully.
11) Non-sub version Rule :-
5) View Updating Rule :-
This rule about the user view if we create any view for any user then it should be up datable.each user required different amount of data for this purpose codde`s suggest that RDBMS package should has a provision to create a view for different user.
6) Integrity Independence Rule :-
This rule about the integrity about of database if any integrity (rule) is impose on any attributes then the maintains of this integrity should be independence from data.
7) Relational Manipulation Rule :-
In all RDBMS package data are store in the form of relation then DR. E.F codde suggest there should be a language that perform operation on relation. Relational algebra and relational calculus is prosigeral RDBMS package that has tools to perform operation on relation there are the some basic operation perform by relational algebrai.e as follow :-
select, projection, Division, Cartesian product, join, set different, union, intersection etc.
8) Physical Data Independency :-
This rule about the data independency it suggest that physical data of a database should independence from logical data.
9) Logical Data in dependency :-
This rule about the maintaining of logical data independence from the external data.
10) High Level Insert, Delete and update :-
This rule is about the interface to performing operation with any RDBMS generally we perform three operations i.e insert,delete and update.this three operation can be perfome sucessfully.
11) Non-sub version Rule :-
This rule about the low level language for handing the database. if it is used then relational principle should not be violate (break down).
12) Distribution Independence :-
This rule about the data distribution if more than one user perform operation on single database then they are unaware from data.
