Relational Database Basic Terminologies


☞ Following are the basic terms related to Relational database.

1. Entity
2. Table/Relation
3. Attributes/Fields/Columns
4. Data Values
5. Tuple/Record/Row
6. Cardinality
7. Degree
8. Domain
9. Body of the Relation
10. Relational Database

Entity

☞ It is a real world object about which information is to be stored in a database.

Example : information about an entity Student in a school.


Table/Relation

☞ It is a collection of logically related records.

☞ It is organised as a set of columns and can have any number of rows.

☞ Collection of records makes a table.

Example : student table can have columns namely name, roll number, admission number etc.


Attributes/Fields/Columns

☞ It is this smallest entity in a database.

☞ Collection of fields make a record.

Example : Hindi student table the field “admno” will hold the admission number of students of a school.


Data Values

☞ Data values are the raw data represented in numeric, character or alphanumeric form.

Example : “Manish”, 26, “Chandigarh”, “10 -07-1998”


Tuple/ Row/Record

☞ The data values for all the fields related to a person or object is called a record.

Example : Hindi student table with the field names as name, class, fees the data values of all the fields for a student maybe (“Ankita”, “X”, 4500.76) and this forms one record.


Cardinality

☞ It is the number of records.


Degree

☞ It is the number of attributes.


Domain

☞ It is the set of all possible values that an attribute may contain.


Body of the Relation

☞ It consists of an unordered set of 0 or more records/tuples.


Relational Database

☞ It is a collection of related tables.