What resources or tutorials would you recommend for learning about SQL joins and optimizing queries for calculating monthly consumption data in PHP applications?

When calculating monthly consumption data in PHP applications using SQL joins, it is important to understand the different types of joins (such as INNER JOIN, LEFT JOIN, RIGHT JOIN) and how they can be used to combine data from multiple tables. Additionally, optimizing queries involves using indexes, avoiding unnecessary calculations, and structuring queries efficiently. 

// Example SQL query to calculate monthly consumption data using INNER JOIN
$query = "SELECT p.product_name, SUM(s.quantity) AS total_quantity
          FROM products p
          INNER JOIN sales s ON p.product_id = s.product_id
          WHERE MONTH(s.sale_date) = :month
          GROUP BY p.product_name";

// Execute the query and fetch the results
$stmt = $pdo->prepare($query);
$stmt->execute([':month' => 5]);
$results = $stmt->fetchAll(PDO::FETCH_ASSOC);

// Display the results
foreach ($results as $row) {
    echo $row['product_name'] . ': ' . $row['total_quantity'] . ' units sold' . PHP_EOL;
}

Keywords

SQL joins query optimization monthly consumption data PHP applications tutorials

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