What is Relational Database, Primary Key, Foreign Key.Wisdom Axis Data Bank.

SQL for BEGINNERS
and DUMMIES

What is SQL, Table,
Database and RDBMS

What is Relational Database

PRIMARY KEY
FOREIGN KEY

Creating Tables and
Inserting Data

CREATE
ALTER
INSERT

Data Reading SQL
Funtions with Examples

SELECT
COUNT
DISTINCT
SUM | MIN | MAX
LIKE
WHERE

What is Relational Database Management System (RDBMS) ?

When related tables are stored in the database - the relation is based on the system/application or subject and the relationship is established between tables using Primary Key and Foreign Key along with referential constraints, we call it as Relational Database Management System (RDBMS).


What is PRIMARY KEY ?

PRIMARY KEY - It creates UNIQUE INDEX on selected COLUMN. This restricts inserting duplicate records for column with Primary Key. Unique Index helps to improve the search performance.


What is FOREIGN KEY ?

FOREIGN KEY - It creates NON-UNIQUE INDEX on selected COLUMN. This Key works in relation with Primary Key, the relation between two tables gets established using Primary Key and Foreign Key.