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Explain the concepts of relational data model?
Relational Data Model - The relational model was first introduced through Prof. E.F. Codd of the IBM Research in the year 1970 and attracted immediate attention because of its simplicity and mathematical foundation. The model uses the concept of a mathematical relation (such as a table of values) as its primary building block, and has its theoretical basis within set theory and first-order predicate logic. The relational model represents the database as a collection of relations. The relational model such as all other models consists of three basic elements:
how the string works as keyword?
Consider the following relational schema: Doctor(DName,Reg_no) Patient(Pname, Disease) Assigned_To (Pname,Dname) Give expression in both Tuple calculus and Domain calculus for
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An Enterprising group of Entrepreneurs introduced a new business named StoreItRite which is based on data storage and retrieval services. It provides the services and the company c
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Illustrate the statement 'Projection operation distributes over the union operation'. Give an example. Ans: Π L (E 1 ∪ E 2 ) = (Π L (E 1 )) ∪ (Π L (E 2 )) This says th
What is a database? Database - Basically in simple terms A database is a collection of inter related data and/or information stored so which it is available to several users
Discuss the differences among the candidate keys and the primary key of a relation. Give instance to describe your answer? A candidate key is one that can be used as primary ke
Explain the Cartesian product: The Cartesian product operation does not need relations to union-compatible. The meaning of this is that the involved relations may have dissim
Describe the four main ways of optimising disk block access. Ans: a. Disk b. Non-volatile writes buffers c. File organization (Clustering) d. Log-based file system
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