如何使用json_encode(数据库中的php数组)结果解决此问题

<?php
// 连接数据库并查询数据
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";

$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

$sql = "SELECT * FROM table";
$result = $conn->query($sql);

$data = array();
if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        $data[] = $row;
    }
}

// 将PHP数组转换为JSON字符串
$jsonData = json_encode($data);

// 输出JSON字符串
echo $jsonData;

// 关闭数据库连接
$conn->close();
?>