Mysqli在jquery中返回逗号分隔值而不查看该值？

<?php
// 连接到MySQL数据库
$mysqli = new mysqli("localhost", "username", "password", "database");

// 检查连接是否成功
if ($mysqli->connect_errno) {
    echo "Failed to connect to MySQL: " . $mysqli->connect_error;
    exit();
}

// 执行查询
$result = $mysqli->query("SELECT column_name FROM table_name");

// 检查查询是否成功
if (!$result) {
    echo "Query failed: " . $mysqli->error;
    exit();
}

// 将查询结果以逗号分隔的形式展示
$values = array();
while ($row = $result->fetch_assoc()) {
    $values[] = $row['column_name'];
}

// 关闭数据库连接
$mysqli->close();

// 将查询结果以逗号分隔的形式输出
echo implode(",", $values);
?>