MySQL Introduction

What is database?

A database is a separate application that stores a collection of data. Each database has one or more distinct APIs for creating, accessing, managing, searching and replicating the data it holds.

Other kinds of data stores can be used, such as files on the file system or large hash tables in memory but data fetching and writing would not be so fast and easy with those types of systems.

So nowadays, we use relational database management systems (RDBMS) to store and manage huge volume of data. This is called relational database because all the data is stored into different tables and relations are established using primary keys or other keys known as foreign keys.

A Relational DataBase Management System (RDBMS) is a software that:

Enables you to implement a database with tables, columns and indexes.Guarantees the Referential Integrity between rows of various tables.Updates the indexes automatically.Interprets an SQL query and combines information from various tables.

RDBMS Terminology:

Before we proceed to explain MySQL database system, let’s revise few definitions related to database.
Database: A database is a collection of tables, with related data.

Table: A table is a matrix with data. A table in a database looks like a simple spreadsheet.

Column: One column (data element) contains data of one and the same kind, for example the column postcode.

Row: A row (= tuple, entry or record) is a group of related data, for example the data of one subscription.

Redundancy: Storing data twice, redundantly to make the system faster.

Primary Key: A primary key is unique. A key value can not occur twice in one table. With a key, you can find at most one row.

Foreign Key: A foreign key is the linking pin between two tables.

Compound Key: A compound key (composite key) is a key that consists of multiple columns, because one column is not sufficiently unique.

Index: An index in a database resembles an index at the back of a book

Referential Integrity: Referential Integrity makes sure that a foreign key value always points to an existing row.

What is MySQL?

MySQL is a open source, fast reliable and flexible relational database management system which are used with Php.

  • MySQL is a database system which is used for the developing web based software application.
  • This is used for both small and large applications.
  • It is relational database management system (RDBMS).
  •  MYSQL supports standard SQL.


  • MySQL server design is multi-layered with independent modules.
  • MySQL is fully multithreaded by using kernel threads.
  • It can use multiple CPUs if they are available.
  • It provides the transaction and non-transactional storage engine.
  • It has very fast thread -based memory allocation system.
  • It supports in-memory heap table.
  • It handles large databases.
  •  MySQL server works in client/server or embedded systems.
  •  It works on many different platforms.

Who uses MySQL?

  • Most popular websites: Facebook, Wikipedia, You Tube, Flickr etc.
  • Content Management System (CMS) like WordPress, Drupal, Joomla, phpBB.