php - MySQL 将一列求和到 LIMIT 并返回求和值

Question

我有一个数据库，我试图用 LIMIT 将一列加总到特定点，然后返回总和值，但它不起作用。这是我的:

<?php 
$servername = "localhost";
$username = "xxxxx";
$password = "xxxxxx";
$dbname = "xxxxxx";

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

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

$sql = "SELECT sum(donation_count) FROM (SELECT donation_count FROM users LIMIT 9) AS value_sum";

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

if ($result-> num_rows> 0) {
    while ($row = $result->fetch_assoc()) {
        echo '<div>'".$row['value_sum']."'</div>';
    }
}
?>

Answer 1

SELECT sum(donation_count) as value_sum FROM (SELECT donation_count  FROM users LIMIT 9) AS temp