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MySQL – Introduction

 

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What is Database?

Before learning MySQL, it is very important to understand the database. A database is an application that stores the organized collection of records. It is very easy for the user to access and manage. By arranging data into tables, rows, columns, and indexes, we can find relevant information very quickly. For performing database operations such as creating, managing, accessing, and searching data, each database contains a separate API. A variety of databases are available today, including MySQL, Sybase, Oracle, MongoDB, PostgreSQL, and SQL Server etc. We will primarily focus on MySQL in this section.

MySQL Database

MySQL is a fast, easy-to-use relational database management system (RDBMS)  that is being used for many small and big businesses. MySQL AB is a Swedish company that develops, markets, and supports MySQL throughout the world. It has become so popular because of its many features, reliability, and ease of use.

  1. MySQL is released under an open-source license, so you do not need to pay for it.
  2. MySQL is a powerful database program that handles some of the same functions as more expensive and powerful packages.
  3. MySQL uses the SQL database language, which is a standard form of well-known standards.
  4. MySQL runs on many operating systems and with many programming languages, including PHP, PERL, C, C++ and Java.
  5. MySQL is a fast and powerful database server that works well with large amounts of data.
  6. MySQL is a friendly program for PHP, the most popular programming language used for web development.
  7. MySQL supports the creation of large databases, up to 50 million rows or more in a table. The default file size limit for a table is 4GB, but you can increase this limit (if your operating system can handle it) to a theoretical limit of 8 TB.
  8. MySQL is a customizable open-source database management system. The GPL license allows programmers to modify MySQL to fit their own specific environments.

RDBMS Terminology

Let’s review a few definitions related to the MySQL database system before getting into the details.

Database – A database is a collection of tables that store related information.

Table – A table is a way to organize data in a database. The tables are organized by rows and columns, just like a spreadsheet.

Column –  One column (data element) contains information about one and the same subject, for example the column postcode.

Row – A row is a collection of related data, such as the data for one subscription.

Redundancy –  We stored data twice, redundantly, in order to make our system faster.

Primary Key – A primary key is unique. It cannot be repeated in one table. A key value can only be found in one row, so you can only find one piece of data at a time.

Foreign Key – A foreign key is a column that links two tables.

Compound Key – A compound key is a key that contains multiple columns, because one column does not have enough unique values.

Index – An index in a database is like the index at the back of a book.

Referential Integrity – Referential integrity ensures that the foreign key values in a table always point to existing rows.