What is RDBMS Lecture -4

What is RDBMS

DBMS:-

                    Data base management system (DBMS) which follows all the 12 rule given by  Dr Edgar F. Codd  known as Relational data base management system (RDBMS)

According to Dr.Edgar F codd rule are as follows

1 Information Rule :- 

                                        This rule states that all information (data) ,which stored in database must be stored in table  formats,this information can be user data or meta -data.

2.Guaranteed Access rule :-

                                        This rule states that every single data element (value) is guaranteed to be accessible logical with combination of table name and primary key .

3.Systematic Treatment of NULL value:-

                      This rule states that NULL value in the database must be given systematic treatment i.e. primary key value never be NULL because NULL have several meaning that cause various anomaly occurs in data base

4.Active online catalog :-

                                      This rule states that the structure of whole database must be stored  in an online catalog i.e. Data Dictionary

5. Comprehensive data sub-language rule :-

                                     This rule states that  database must have support for a language which has linear syntax which is capable of Data Definition ,Data Manipulation,Data control  

6.View Updating rule:-

                               This rule states that all system should able to updates all views of database  without any anomaly in the system

7. High-level insert -Update and Delete rule:-

                               This rule states that system must support high level insertion,updation ,deletion this must not be limited to a single row that it must support join operations to yield set of data

8. Physical data independence:-

                              This rule states that application should not have any concern about ,how the data physically stored in the system as well as any change in physical structure must not have any impact on application 

9.Logical Data Independence:-

                            This rule states that logical data must be independent of its user's view as well as any change in logical data must not imply any change in the application .e.g. if two table are merged or one is split into two different table there should be no impact on the application

10.Integrity Independence:-

                               This rule states that all integrity constraints can be independently modified without the any change in the application.this rule makes database independent of front-end application and its interface.

11.Distribution Independence:-

                      This rule states that the end user must not be able to see that the data in distributed over various locations,end user have feel that data is located at one site only. 

12. Non-subversion rule:-

                              This rule states that if system has an interface that provides access to low level records ,this interface then must not be able to subvert the system and bypass security and integrity constraint 

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