How Can I Execute Multiple MySQL Queries Simultaneously?

Why Can't I Run Multiple mysqli Queries Simultaneously?

As you've noticed, attempting to execute two separate MySQL queries using consecutive mysqli_query() calls will result in the second query failing. This behavior is due to security measures.

mysqli_multi_query() to the Rescue

Fortunately, mysqli provides the mysqli_multi_query() function specifically designed for executing multiple queries in a single database call.

Example Code

Here's an example of how to use mysqli_multi_query():

$mysqli = new mysqli($host, $user, $password, $database);

// Create query string with multiple queries separated by ;
$query  = "INSERT INTO images (project_id, user_id, image_name, date_created, link_to_file, link_to_thumbnail, given_name) VALUES ('$project_id', '$user_id', '$image_name', '$date_created', '$link_to_file', '$thumbnail', '$ImageName');";
$query .= "INSERT INTO images_history (project_id, user_id, image_name, date_created, link_to_file, link_to_thumbnail, given_name, day, month, year) VALUES ('$project_id', '$user_id', '$image_name', '$date_created', '$link_to_file', '$thumbnail', '$ImageName', '$day', '$month', '$year');";

// Execute query using mysqli_multi_query()
$result = mysqli_multi_query($mysqli, $query);

// Retrieve results
if ($result) {
    do {
        $result = mysqli_store_result($mysqli);
    } while (mysqli_more_results($mysqli) && mysqli_next_result($mysqli));
} else {
    echo "First query failed: " . mysqli_error($mysqli);
}

Additional Considerations:

• mysqli_store_result() will return FALSE for queries without result sets, such as INSERT queries. Check mysqli_error() to confirm successful execution.
• Note the use of ";" as the separator between queries.

By using mysqli_multi_query(), you can efficiently execute multiple queries in a single database call, avoiding the second query failure issue.

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