FUNDAMENTALS OF COMPUTER

Detailed explanation-1: -A relation, also known as a table or file, is a subset of the Cartesian product of a list of domains characterized by a name. And within a table, each row represents a group of related data values. A row, or record, is also known as a tuple. The columns in a table is a field and is also referred to as an attribute.

Detailed explanation-2: -Tuple : Row of the relation, depicting a real-world entity. Attribute/Field : Column of the relation, depicting properties that define the relation. Attribute Domain : Set of pre-defined atomic values that an attribute can take i.e., it describes the legal values that an attribute can take.

Detailed explanation-3: -According to the preceding definition of a relation the ordering of values in tuple is important. However at a logical level, the order of attributes and their values is not that important as long as the correspondence between attributes and values is maintained. Each value in a tuple is an atomic value.

Detailed explanation-4: -Relation instance – Relation instance is a finite set of tuples in the RDBMS system. Relation instances never have duplicate tuples. Relation key – Every row has one, two or multiple attributes, which is called relation key.