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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 completeness constraint on generalization? Define the variation between total and partial design constraint. Give an example each. Ans: Completeness Constraints
losers with new information systems
Explain mechanism of nested queries? SQL gives a mechanism for nesting subqueries. A subquery is a select from where expression that is nested within one more query. A common u
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Extend your CREATE TABLE statement from problem 3 with referential integrity constraints. Updates and deletes on related rows are restricted. 6. From examination of the sample data
What is nested relational model? The nested relational model is an extension of relational model in which domains might be either atomic or relation valued.
While sorting field groups we cannot use more than one key field False.
A video rental company has several branches. The data held on each branch is the branch address made up of street, city, state, and zip code, and the telephone number. Ea
Rearrange Classes and Operations Sometimes, the similar operation is defined across different classes and can easily be inherited from a familiar ancestor, but more often oper
What is trigger Triggers are statements that are implemented automatically by the system as the side effect of a change to the database.
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