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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:
entity relationship diagram for online examination system
What is difference between primary index and secondary index? Primary Index a) It is an ordered file whose records are of fixed length along with two fields. b) Only base
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Define According to the levels of abstraction, the schema at the intermediate level is called Ans: As per to the levels of abstraction, the schema at the intermediate level is
If R1 and R2 are two union compatible relations or functions, then the result of R3 = R1 ∩R2 is the relation that contains all tuples that are in both the relations In other words,
Define Atom of domain relational calculus An atom has the outline 1 , x 2 , ... , x n > -> r , in which r stands for a relation on n attributes and x 1 , x 2 , ... , x n ar
What is an ER diagram? Why is it used in Database management system (DBMS)?
What is first normal form? The domain of attribute must contain only atomic (simple, indivisible) values.
Design a database for an airline.The database must keep track of customers and their reservations,flights and their status, seat assignment on individual flights and, the schedule
#questiononsider the following relation: CAR_SALE =(CAR_ID,oPTION_TYPE, Option_listpreice, Sale_date, Option_discountedprice)..
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