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Connecting with PHP

This guide explains how to establish a connection between a PHP application and a MySQL database using the mysqli extension. It walks through the necessary setup, configuration, and execution of a simple SQL query.

Variables

Certain parameters must be provided to establish a successful connection to a MySQL database. Below is a breakdown of each required variable, its purpose, and where to find it. Here’s what each variable represents:

Variable

Description

Purpose

USER

MySQL username, from the Elestio service overview page

Identifies the database user who has permission to access the MySQL database.

PASSWORD

MySQL password, from the Elestio service overview page

The authentication key is required for the specified USER to access the database.

HOST

Hostname for MySQL connection, from the Elestio service overview page

The address of the server hosting the MySQL database.

PORT

Port for MySQL connection, from the Elestio service overview page

The network port used to connect to MySQL. The default port is 3306.

DATABASE

Database Name for MySQL connection, from the Elestio service overview page

The name of the database being accessed. A MySQL instance can contain multiple databases.

These values can usually be found in the Elestio service overview details as shown in the image below, make sure to take a copy of these details and add it to the code moving ahead.

image.png

Prerequisites

  • Install PHP
    • Check if PHP is installed by running: php -v
    • If not installed, download it from php.net and install.
    • Make sure the mysqli extension is enabled in your php.ini configuration.

Code

Once all prerequisites are set up, create a new file named mysql_connect.php and add the following code:

<?php
$host = "HOST";
$user = "USER";
$password = "PASSWORD";
$database = "DATABASE";
$port = PORT;

// Create connection
$conn = new mysqli($host, $user, $password, $database, $port);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
echo "Connected to MySQL<br>";

// Run a test query to check the MySQL version
$result = $conn->query("SELECT VERSION()");

if ($result) {
    $row = $result->fetch_assoc();
    echo "MySQL Version: " . $row["VERSION()"];
    $result->free();
} else {
    echo "Query execution failed: " . $conn->error;
}

// Close connection
$conn->close();
?>

To execute the script, run the PHP server in the directory where mysql_connect.php is located using:

php -S localhost:8000

Then, open a browser and go to:

http://localhost:8000/mysql_connect.php

If the connection is successful, the browser will display output similar to:

Connected to MySQL
MySQL Version: 8.0.36
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