PHP and MySQL Fundamentals

PHP Definition

• PHP stands for "PHP HyperText Preprocessor."
• The first "P" in PHP is an abbreviation of "PHP."
• Created in 1994.
• Version 7.3.7 is the most recent stable version (as of July 15, 2019).

Role of PHP

• Enables the creation of dynamically generated pages.
• Displaying different content on the same page based on variables, example: time of day or user login status. PHP and E-Commerce Client Spaces:
• Used on e-commerce websites for personalized client spaces, showing order history, billing info, and shipping addresses.
• User login information is processed and analyzed.
• Specific user information is retrieved, and pages are dynamically generated.
• User data like addresses and phone numbers are stored in databases; PHP retrieves this data.
• Executed server-side, part of "server-side" languages as opposed to "client-side" languages.

Static vs Dynamic Sites

• Web-focused programming languages are categorized into static and dynamic.
• Static sites lack interaction and adaptation.
• Code doesn't change based on users or variables.
• Suitable for CVs or informative websites.
• HTML and CSS-only sites are static.
• Dynamic sites provide pages that are different for each user, allow user interaction and data submission.
• PHP is used for calculation and data processing, paired with MySQL for database management.
• Websites created with client-side languages are static; those using client-side and server-side languages are dynamic.

My SQL Definition

• MySQL is a system for managing relational databases.
• A database is a structured collection of data.
• Data includes info like client details, blog comments, article content, etc.
• Direct interaction with databases isn't possible due to the way data is stored.
• Requires a database language to manipulate stored data.
• SQL (Structured Query Language) is the most common database language.
• The MySQL database management system uses SQL to manipulate database data.
• MySQL is simple, reliable, and high-performing, enabling management of multiple database types.
• Can be jointly used with PHP.

Common Usage

• Used for user registration and identification on a site.
• HTML forms collect user data, then PHP retrieves the form data.
• The data is stored in a database, which functions as a file.
• Databases can be created either with PhpMyAdmin or by sending SQL queries from a code file.
• PHP extensions such as PDO or MySQLi are used to code in MySQL.
• SQL queries in MySQL code create and populate the database.
• The MySQL system manages, organizes, and secures the database file.
• MySQL is a "relational" system, storing data in multiple linked tables.
• Creating and manipulating databases requires a database management system.

Why use PHP and MySQL

• Unlike HTML and CSS, PHP and MySQL have multiple competitors.
• Alternatives to PHP: Python, Ruby, JavaScript.
• Alternatives to MySQL: PostGreSQL, Microsoft SQL Server, MariaDB.
• PHP/MySQL remains popular for creating dynamic sites and storing data.
• PHP's structure is easy for beginners to grasp, with support for complex structures.
• PHP is open source and free and works across most platforms.
• Open source nature means continuous improvement solidifying performance and security.
• Database management systems rely on SQL standards.
• MySQL chosen for course due to popularity and compatibility with PHP.
• Compatible with PHP, uses standard SQL syntax, simple, robust, and high-performing.

Client Side vs Server Side Languages

• A website is a collection of linked code files and media resources.
• Code within these files can be executed either client-side in the user's browser or server-side.
• Browsers can only process HTML, CSS, and JavaScript code, not PHP.
• When a browser requests a page, the server executes any non-understandable code and returns the result in a browser-compatible format like HTML.
• Server-side operations are invisible to the user and the browser only shows understandable code.
• When analyzing page code, only HTML, CSS, and JavaScript are visible, not PHP.

Writing PHP

• WAMP or XAMPP is used to execute PHP code.
• A text editor is needed to write the code.
• PHP scripts can be written either in dedicated .php files or within HTML files.
• Files containing PHP must be saved with the .php extension.
• The server needs to recognize PHP code using the tags.
• The tags and PHP code can be placed anywhere in an HTML document.

Basic Syntax

• A first PHP instruction analyzes and understands general syntax.
• The first line contains a single-line comment, and comments explain or disable instructions.
• Comments are ignored during execution.
• Two comment syntaxes: // for single-line and /* */ for single or multi-line.
• The echo parts of strings are instructions that make something happen.
• Structure displays a string of characters in this case, Hello World and Bonjour le Monde.
• PHP instructions must end with a semicolon.
• The br element inside the first text element is not displayed but inserts a line break in the browser.
• Server executes the code requests a page and returns browser-understandable code such HTML.
• The server executes instructions and sends HTML, including the HTML br to the browser.
• File with a PHP extension is required to open a PHP file.
• To execute PHP code, software that was previously installed is required.
• Open a new tab in the browser providing the localhost address.
• To access the content, in the browser the relevant file is available in the folder that the file is saved in.
• When opening a file without going through server the code will be displayed normally and will not be executed.

Language Syntax

• Language structure corresponds simply to part of language syntax.
• Computing language syntax corresponds to a set of keywords with well-defined meanings.
• Language structures are the basic units which expressions are constructed from.

Echo and Print Structures

• Language structures output a result in PHP.
• Write our echo or our print statement in a PHP tag and include a semicolon to terminate the string.
• An alternative syntax exists that involves a set of parentheses for echo and print.

Variables

• A variable is a container or temporary storage that stores a value.
• Variables are created within a script.
• Choosing a variable name is flexible, with naming rules for new variable declarations:
  • Start with the $ sign, followed by the name.
  • The name must start with a letter or underscore, not a number.
  • Limited to letters, numbers, and underscores.
  • No spaces are allowed.
• PHP variables are case-sensitive ($texte, $TEXTE, and $tEXTe are different).
• There are reserved names that cannot be used.
• $prenom and $age create two variables that will store a character string and then a number.

Display and Modify Contents

• Performing operations with variables occurs in PHP.
• The most basic operation echo can output the contents of a PHP variable.
• The equal sign used above is not a comparative operator but an assignment operator, which serves to assign a value to a variable.
• = sign does not represent equality from a mathematical consideration.
• Equality is represented by == sign.
• Equality in terms of value and data type, which identity, is represented in PHP by ===.
• Variables store strings of characters, integers, or decimal numbers.
• Using quotation marks and apostrophes indicate that the value stored will be a string of characters.

Explore the fundamentals of PHP and MySQL. Learn about PHP's server-side execution, customization capabilities, and database interaction. Discover MySQL's role in data management and its integration with PHP through interfaces like PDO and MySQLi.