How can PHP be used to link multiple database tables together for efficient data retrieval?

To link multiple database tables together for efficient data retrieval in PHP, you can use SQL JOIN statements to combine the tables based on a common column. By using JOINs, you can retrieve related data from multiple tables in a single query, reducing the number of queries needed and improving performance. 

<?php
// Connect to the database
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";
$conn = new mysqli($servername, $username, $password, $dbname);

// Query to retrieve data from multiple tables using JOIN
$sql = "SELECT users.username, orders.order_id, orders.total_amount
        FROM users
        JOIN orders ON users.user_id = orders.user_id";
$result = $conn->query($sql);

// Loop through the result set and display the data
if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        echo "Username: " . $row["username"]. " - Order ID: " . $row["order_id"]. " - Total Amount: " . $row["total_amount"]. "<br>";
    }
} else {
    echo "0 results";
}

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

Keywords

PHP database tables data retrieval linking efficient

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