PHP and MySQL Comparative Terms every Web Developer should know

In the previous article, we explored some key terms in HTML, CSS, and JavaScript—essential building blocks that help clarify web development concepts. Now, let’s take it a step further! In this article, we’re diving into some important comparative terms in PHP Core and MySQL. These terms aren’t just helpful—they’re crucial for strengthening your foundation in backend development. Whether you’re just starting out or looking to solidify your understanding, this is where the backend magic begins!

Table of contents:

• PHP
• MySQL

1 – PHP

1.1 – What is the difference between Procedural Programming and Object-Oriented Programming?

1 – Procedural programming is about writing procedures or functions that perform operations on the data. 1 – Object-oriented programming is about creating objects that contain both data and functions.

2 – Procedural programming focuses on a linear sequence of steps. 2 – Object-oriented programming focuses on creating objects that interact with each other to solve problems.

3 – In procedural programming, data and functions are separate entities. Data is typically stored in variables, and functions are used to perform operations on that data. 3 – In object-oriented programming, classes and objects are two main aspects. A class is a blueprint that defines the structure and behavior of objects, while an object is an instance of a class.

4 – In procedural programming, data can be accessed globally. 4 – In object-oriented programming, it supports different access modifiers like private, public, and protected to access the data.

5 – Procedural programming promotes code reusability through the use of functions, which can be called from different parts of the program. 5 – Object-oriented programming offers benefits like encapsulation, inheritance, and polymorphism for code reusability.

1.2 – What is the difference between Session and Cookie in PHP?

1 – Session stores data on the server-side. The server maintains a record of user interactions and data associated with a unique session ID. 1 – Cookie data is stored on the client-side, within the user’s web browser as small text files.

2 – Session allows you to store user-specific information, such as login credentials, shopping cart items, and other data. 2 – Cookie allows you to store personalize user experiences, user preferences, and session information.

3 – Session is secure as it is not on the user’s computer so you can store sensitive data on the session. 3 – Cookie is not secure as it is on the user’s computer so you can not store sensitive data on the cookie.

4 – To start a session, you need to use session_start() function. The session_start() function must be very first thing in the document. 4 – To start a cookie, you need to use setcookie() function.

5 – To remove all global session variables and destroy the session, use session_unset() and session_destroy() functions. 5 – To delete a cookie, use the setcookie() function with an expiration date in the past.

1.3 – What is the difference between include(), include_once(), require(), and require_once()?

In PHP, require, require_once, include, and include_once are used to incorporate the content of one file into another. The primary differences lie in their error handling and whether they prevent duplicate inclusions.

require:

• If the file is not found or cannot be included, it generates a fatal error (E_COMPILE_ERROR) and halts the script’s execution.
• This is suitable for essential files like configuration files or core libraries.

include:

• If the file is not found or cannot be included, it generates a warning (E_WARNING) and allows the script to continue execution.
• This is suitable for optional files or templates where the script core functionality doesn’t depend on the included file.

require_once:

• Checks if the file has already been included. If it has, it won’t include it again.
• This is the most common and robust way to include essential files.

include_once:

• Checks if the file has already been included. If it has, it will not include it again.
• This is a safer way in many cases to avoid unintended side effects.

1.4 What is the difference between == and === in PHP?

1 – == This operator checks if the values of the two operands are equal. 1 – === This operator checks if both the values and the data types of the two operands are identical.

2 – == PHP will attempt to convert the variables to a common type before comparing them. 2 – === No type conversion occurs in the strict equality operator.

3 – == example: $a = 5; // Integer $b = “5”; // String var_dump($a == $b); // Output: bool(true) 3 – === example $a = 5; // Integer $b = “5”; // String var_dump($a === $b); // Output: bool(false)

2 – MySQL

2.1 – What is the difference between Primary key and Foreign key?

1 – Primary key uniquely identify each record (row) in a database table. 1 – Foreign key establish and enforce a relationship between two tables, ensuring that the data in one table corresponds to valid data in another.

2 – All values in the Primary key column must be unique; no duplicate values are allowed. 2 – Foreign key can have duplicate values.

3 – A Primary key cannot contain NULL values. 3 – A Foreign key can accept NULL values.

4 – A table can have only one Primary key. 4 – A table can have multiple Foreign keys, linking to different tables.

2.2 – What is the difference DELETE and TRUNCATE?

1 – The DELETE command is used to delete particular records from a table. 1 – The TRUNCATE command is used to delete the complete data from the table.

2 – The DELETE command works with the WHERE clause. 2 – The TRUNCATE command does not work with the WHERE clause.

3 – You can restore the data using the COMMIT or ROLLBACK command. 3 – You cannot restore the deleted data after executing this command.

4 – The DELETE is a Data Manipulation Language Command. 4 – The TRUNCATE is a Data Definition Language Command.