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Describe entity referential integrity and integrity. Give an example of each.
Entity Integrity Rule - If there is a attribute A of relation R is a prime attribute of R then A cannot accept null values.
Referential Integrity Rule - In referential integrity, it is ensured in which a value in which appears in one association for a given set of attributes also appears for a certain set of attributes in another relation.
For example:
Roll No is the primary key within the relation STUDENT and Roll No + Course is the primary key of the relation GRADE. (Entity Integrity) Roll No in the relation GRADE (child table) is a foreign key, which is referenced from the relation STUDENT (parent table). (Referential Integrity).
What is data integrity? Ans: It is the data consisted of in database that is accurate and consistent. (Data integrity means that the data should be valid as per to the give
Data Independence This brings us to our next topic: data independence. It is the property of the database which tries to make sure that if we make any change in any level of sc
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The advantages of a database management system (DBMS) include :- Data integrity and elimination of duplication.
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Rules Of Data Normalisation Let us now summarise Normalisation with the help of various clean rules. The following are the necessary rules for the Normalisation process: 1.
What are the reasons for having variable length records? What are the various ways to store variable length records? Variable-length records arise in a database in various wa
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