What is the best practice for joining tables in PHP queries?

When joining tables in PHP queries, it is best practice to use SQL JOIN statements to combine data from multiple tables based on a related column between them. This allows you to retrieve data from multiple tables in a single query, reducing the need for multiple queries and improving efficiency. 

<?php
// Connect to the database
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";

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

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

// SQL query with JOIN statement
$sql = "SELECT orders.order_id, customers.customer_name
        FROM orders
        JOIN customers ON orders.customer_id = customers.customer_id";

$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // Output data of each row
    while($row = $result->fetch_assoc()) {
        echo "Order ID: " . $row["order_id"]. " - Customer Name: " . $row["customer_name"]. "<br>";
    }
} else {
    echo "0 results";
}

$conn->close();
?>

Keywords

SQL JOIN PHP PDO INNER JOIN LEFT JOIN ON clause

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