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Explain Domain calculus
Domain calculus is one of the types of the relational calculus. The formal specification of the domain calculus was planned after the development of the QBE system. Domain calculus has the variables range in excess of single value from domains of attributes. To create a relation degree n for a query result, we should have n domain variables - one for each attribute. An expression of the domain calculus is of the form {X | F(X)}
In which F is a formula on X and X denotes a set of domain variables. The expression characterizes X like F(X) is true.
What are axioms? Axioms or rules of inference give a simpler technique for reasoning about
Synonyms It allows short names or alternative names for objects. Example : CREATE SYNONYM D30 FOR EMPD30; Now if we give command:
What is OOM? Object oriented modeling is an approach by which modeling of systems is done by visualizing the system based on real world concepts. Object oriented modeling does
One-to-many : An entity in A is related with any number of entities in B. An entity in B is related with at the most one entity in A. Example: Relationship between faculty and d
In an E-R diagram how attributes are represented ? In an E-R diagram attributes are represented in a ellipse.
Define an operator that a Relational Algebra does not have Ans: Relational Algebra does not have Aggregation operators.
What is assertion? Mention the forms available. An assertion is a predicate expressing a condition that we wish the database always to satisfy. Domain integrity constraints.
What is a guard condition? Explain it with a suitable example. The guard-condition is a Boolean expression written with respect to parameters of triggering event and attributes
The indices are accumulated in the index files. The data is accumulated in the data files. Indices give fast access to data items. For example, a book database may be managed in th
How can we Classify the operations on classes This step fundamentally means all three models functional, object and dynamic (studied in last section) must be combined so that
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