How to retrieve Data from MySQL Database Using PHP

Learn how to retrieve data from a MySQL database using PHP. Includes detailed code and explanation on how to connect to and query a MySQL database.

Here is the PHP code to connect to and retrieve data from a MySQL database:

<?php
$servername = "localhost";  // Database server address
$username = "root";         // Database username
$password = "";             // Database password
$dbname = "my_database";    // Database name

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// Execute SQL query
$sql = "SELECT id, name, email FROM users";
$result = $conn->query($sql);

// Check and display data
if ($result->num_rows > 0) {
    // Output data of each row
    while($row = $result->fetch_assoc()) {
        echo "ID: " . $row["id"]. " - Name: " . $row["name"]. " - Email: " . $row["email"]. "<br>";
    }
} else {
    echo "0 results";
}

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

Explanation of Each Line of Code:

1. Initialize Connection Information:

   • $servername: Database server address, usually "localhost".
   • $username: Database username.
   • $password: Database password.
   • $dbname: The name of the database to connect to.

2. Create Connection:

   • new mysqli($servername, $username, $password, $dbname): Creates a MySQLi connection object with the provided information.

3. Check Connection:

   • if ($conn->connect_error): Checks if there was an error connecting. If there is an error, the script stops and displays an error message.

4. Execute SQL Query:

   • $sql = "SELECT id, name, email FROM users";: Prepares the SQL statement to retrieve data from the users table.
   • $result = $conn->query($sql);: Executes the SQL statement and stores the result in the $result variable.

5. Check and Display Data:

   • if ($result->num_rows > 0): Checks if there are any results returned.
   • while($row = $result->fetch_assoc()): Iterates through each row of data and prints out information for each row.

6. Close Connection:

   • $conn->close();: Closes the database connection after the task is completed.

PHP Version:

The provided code is compatible with PHP version 5.6 and above. MySQLi functions and methods are supported in these versions.