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Define the following in term of relational model?

Domain


Domain denoted by D. Every attribute has some pre-defined value scope, known as attribute domain. Domain D is a set of atomic values (indivisible).Data type or format is to be specified for each domain.

Ex.
Name: set of characters strings that represent names of person.

Employee_ages: Possible age of employees must be integer values between 15 to 80.
Academic_department_codes: values must be ‘CS’, ’ECON’, ‘PHYS’.



Attribute 


In a relation table, each column is called by its column name or attribute name .
the name of a role played by a domain in that relation
Exa- s-name, s-id, s-add etc.


Tuple 


A single row of a table, which contains a single record for that relation is called a tuple.


Relation


A Database structured to recognize relation between stored items as information.


Relation schema 


Relation Schema denoted by R. A relation schema describes the relation name(table name), attributes, and their names.
R(A₁,A₂,…,An), relation name and list of attributes (each of which has a name and a domain)


Relation State 


A set of tuples. Each tuple is an ordered list of values, corresponding with the domain of their attribute, and representing a fact. A relation state is a subset of the Cartesian product of the domains defining the relation schema.
(r ) R set of n-tuples r={ t1+t2+………….tn } each n tuple is an ordered list of n values .
t={ v1+v2+……...vn }


Degrees of Relationship (Cardinality)


 The degree of relationship (also known as cardinality) is the number of occurrences in one entity which are associated (or linked) to the number of occurrences in another.
There are three degrees of relationship, known as:
  1. one-to-one (1:1)
  2. one-to-many (1:M)
  3. many-to-many (M:N)
The latter one is correct, it is M:N and not M:M.


Relation Database Schema



Set of relation schema S = (R1,R2……..Rn) an set of integrity constraints.

Relation Database State



Set of relation states DB ={r1,r2……..rn} each r is a state of Ri and such that the ri relation states integrity constraints specified in

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