24-01-2012, 12:32 PM
The Relational Model
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Introduction
Relational Database
a) Attributes and Domains
b) Tuples
c) Relations and Their Schemes
d) Relation Representation
e) keys
f) Relationships
g) Integrity Rules
Relational Algebra
Relational Operation
Attributes : Attribute is correspond to fields.
Fields: Fields are refer to smallest item of data that are used to capture some specific property of the object.
Sets of attributes are denoted by uppercase letters from the end of the alphabets such as :NAME,AGE,ADDRESS
Types of Attributes
Domain :The set of allowed values for each attribute is called the domain of the attribute
Attribute values are (normally) required to be atomic; that is, indivisible
The special value null is a member of every domain
The null value causes complications in the definition of many operations