DBMS RDBMS Concepts

RDBMS stands for relational database management system. A relational model can be represented as a table of rows and columns. A relational database has following major components:

1. Table
2. Record or Tuple
3. Field or Column name or Attribute
4. Domain
5. Instance
6. Schema
7. Keys

1. Table
A table is a collection of data represented in rows and columns. Each table has a name in database. For example, the following table “STUDENT” stores the information of students in database.

2. Record or Tuple
Each row of a table is known as record. It is also known as tuple. For example, the following row is a record that we have taken from the above table.

3. Field or Column name or Attribute The above table “STUDENT” has four fields (or attributes): Student_Id, Student_Name, Student_Addr & Student_Age.

4. Domain
A domain is a set of permitted values for an attribute in table. For example, a domain of month-of-year can accept January, February,…December as values, a domain of dates can accept all possible valid dates etc. We specify domain of attribute while creating a table.
An attribute cannot accept values that are outside of their domains. For example, In the above table “STUDENT”, the Student_Id field has integer domain so that field cannot accept values that are not integers for example, Student_Id cannot has values like, “First”, 10.11 etc.

5. Instance and Schema
Please read about instanes and schema from here Instances and Schemas

6. Keys Please read about keys from here Keys