Relational Database

What is DBMS ?

• DBMS stands for Data Base Management System.
• A DBMS is an organised collection of data stored in hierarchy form or functional form.
• One set of software provides access of data to all the users.

What is RDBMS?

• It was introduced in by E. F. Codd.
• Basically it is also a Data Base Management  System used to store the data.
• It stores the data in the form of the table.
• Each table contains:
• Field
• Record

What is a Table?

• Table is a collection of related data entries.
• Contains Rows and Columns to store data.

What is a Field?

• The name of the each information in the record.
• It is identity of the specific data in the record.
• This is the First Row of the Table.

What is a Record?

• Record is nothing but details of each individuals person / content of a particular aspect.
• Each individual entity of a group as separate record.
• This are the Row in the Table.

What is a Column?

• Particular Field details of all records in a table.

Constraints:

• Limits the data for specific range.
• Specifies the type of data to be created/ inserted into table.
• List of Constraints:
• NOT  NULL           -   Null Value shouldn't be there in the table.
• DEFAULT              -   Provides a default value of column when non is specified.
• UNIQUE                -   All values must be different.
• PRIMARY KEY     -   Unique identification for each row in table.
• FOREIGN KEY     -   Identifies the unique value in a different record.

Integrity:

• It warns and alerts about restrictions and rules(customized) for the user, to make data safe.
• Below are some integrity used in database.
• Entity                   -    No Duplicate row in table.
• Domain                -    Restricts type, format or range for valid entries.
• User Defined       -    Checks the business rules defined by user.
• Referential           -    Row cannot be deleted, if used by the other records.