Lesson 6.1. Introduction to MySQL

Introduction

MySQL is a database management system relational data. It is one of the most used systems in the world and especially in data storage for web servers.

When creating a website, MySQL will allow to record and keep data on the server disk. Unlike sessions or cookies, this data will be kept as long as necessary. here are some examples of data typically stored in a MySQL database:

• user data;
• passwords, always encrypted ;
• comments or messages;
• the content of the pages;
• statistics on site traffic;
• ...

An optimization database

MySQL offers many features that would be difficult to reproduce with such a level of performance:

• MySQL is optimized for data storage;
• MySQL is fast;
• MySQL is secure;
• MySQL uses the standard SQL protocol;
• MySQL is cross-platform;
• MySQL can be queried from a PHP script.

With MySQL you can store millions of data. But above all, this system was designed from the start to allow quick access to this data. You can find, add or delete data with a single command line that will run in milliseconds.

Structure

MySQL databases are structured according to the following scheme:

• A MySQL base is composed of several databases.
• Each database is made up of several tables.
• Each table consists of several columns and rows.
• The columns contain fields from the table (for example: last name, first name ...)
• Each line contains the data associated with the fields (for example: Pierre, Dupont ...)

A relational database

The last advantage of MySQL is the relational side of its structure. You can link data together. Take for example a database which contains two tables:

• the users table contains the user data;
• the how table contains the comments posted on a website.

Relational databases allow these two tables to be linked, For example to associate user with each message. We will not discuss the relational side of databases here, but remember that the use of relational tables is far from being marginal in Web development.

See also

• Web development class
• Lesson 1.1. History of the Internet
• Lesson 1.2 Introduction to HTML
• Lesson 1.3. Special characters in HTML
• Lesson 1.4. Comments in HTML
• Lesson 1.5. Global structure of HTML pages
• Lesson 1.6. Hyperlinks in HTML
• Lesson 1.7. ID attribute in HTML tags
• Lesson 1.8. HTML anchors
• Lesson 1.9. Images in HTML pages
• Lesson 1.10. HTML tables
• Lesson 1.11. Most used HTML tags
• Lesson 1.12. Some advice
• Lesson 1.13. Ressources
• Lesson 2.1. Introduction to CSS
• Lesson 2.2. Inline CSS
• Lesson 2.3. Internal CSS
• Lesson 2.4. External CSS
• Lesson 2.5. CSS selectors
• Lesson 2.6. CSS colors
• Lesson 2.7. Margin and padding
• Lesson 2.8. CSS units
• Lesson 2.9. Most used CSS properties
• Lesson 3.1. History of JavaScript
• Lesson 3.2. JavaScript Hello World
• Lesson 3.3. Console.log
• Lesson 3.4. Comments in JavaScript
• Lesson 3.5. Variables in JavaScript
• Lesson 3.6. JavaScript events
• Lesson 3.7. Document Object Model (DOM)
• Lesson 3.8. Changing HTML
• Lesson 3.8. JavaScript frameworks
• Lesson 4.1. Introduction to PHP
• Lesson 4.2. PHP tags
• Lesson 4.3. PHP variables
• Lesson 4.4. isset vs empty vs is_null
• Lesson 4.5. PHP operators
• Lesson 4.6. PHP quotes
• Lesson 4.7. Tests in PHP: if .. else
• Lesson 4.8. PHP arrays
• Lesson 4.9. PHP loops
• Lesson 4.10. PHP sessions
• Lesson 5.1. HTML forms
• Lesson 5.2. HTML forms, POST or GET?
• Lesson 5.3. Input fields
• Lesson 5.4. HTML form fields
• Lesson 6.2. phpMyAdmin
• Lesson 6.3. SQL queries
• Lesson 6.4. Connect to MySQL in PHP
• Lesson 6.5. SQL queries in PHP
• Lesson 6.6. Getting data from MySQL in PHP
• Lesson 6.7. Get last ID

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