WHAT IS RDBMS?

RDBMS stands for RELATIONAL DATABASE MANAGEMENT SYSTEM. ,All modern database management system like SQL, Ms SQL Server, IBM DB2, ORACLE, My-SQL and Microsoft access are based on RDBMS. RDBMS is most commanly used database

COMPONENTS OF RDBMS

A Relational database has following major components are:

• Table.
• Record or Tuple.
• Field or column name or attribute.
• Domain.
• Instance.
• Schema.
• Keys.

TABLE

A table is collection of data represented in rows and columns.

RECORD or TUPLE

Each rows of a table is known as Record. It is also known as tuple.

FIELD/COLUMN/ATTRIBUTE

A field is an element in which one piece of information is stored. either a column is collection of cells alligned vertically in atable.

DOMAIN

A domain is a set of permitted values for an attribute in table.

INSTANCE

Instance or extension or database state is a collection of information that stored in a database at a particular moment is called an instance of the database.

SCHEMA

The overall design of the database is called as database Schema. schema will not change frequently. it is logical structure of a datbase.

"A DATABASE SCHEMA IS THE SKELETON STRUCTURE THAT REPRESENTS THE LOGICAL VIEW OF THE ENTIRE DATABASE."

There are three types of schema are:

• Physical Schema.
• Logical Schema.
• External Schema.

KEYS

Keys are very important part of Relational database models. A key can be single attribute or a group pf attributes, where the combination may act as a key.

There are different types of keys are:

• Super Key.
• Primary Key.
• Candidate Key.
• Alternate Key.
• Foreign Key.
• Compound/Composite Key.
• Surrogate key.