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Define functional and multivalued dependencies.
Ans: A functional dependency is a assets of the semantics of the attributes in a relation. The semantics point out how attributes relate to one another, and identify the functional dependencies between attributes. While a functional dependency is available, the dependency is fixed as a constraint among the attributes. Refer a relation with attributes A and B, in which attribute B is functionally dependent on attribute A. If we know the value of A and we inspect the relation that holds this dependency, we will find out just only one value of B in all of the tuples which have a given value of A, at any moment in time. Note though, that for a given value of B there may be various different values of A.
Multivalued Dependencies: A multivalued dependency is an outcome of two independent 1: N relationships A: B and A: C being mixed in similar relation R(A,B,C)
What are domain constraints? A domain is a set of values that might be assigned to an attribute .all values that appear in a column of a relation must be taken from the similar
Which method is used to key transformation ? A hash method is used to key transformation.
Example: Consider the following relations: ROLLNO NAME ADDRESS COURSE_ID 100 Ka
The Database Approach In order to overcome the limits of a file system, a new approach was needed. Hence a database approach emerged. A database is a persistent collection of
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What are the various states through which a transaction passes through in its lifetime? Briefly discuss all the events that causes transition from one state to another. Ans:
Give the levels of data abstraction? There are three levels of Data Abstraction a) Physical level b) logical level c) view level
why older data models are being replaced by new data models.
What is relationship instance ? Relationship Instance - A relationship is a relation between two or more entities. An instance of relationship set is a set of relationships.
I need to Map an E-R diagram to a relational schema
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