在PHP / MYSQL中查找最近的邮政编码位置

<?php
// 用户输入的邮政编码
$userPostalCode = $_POST['postal_code'];

// 连接到MYSQL数据库
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database_name";

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

// 检查连接是否成功
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 查询最近的邮政编码位置
$sql = "SELECT postal_code, location FROM postal_codes ORDER BY ST_DISTANCE(postal_codes.location, POINT_FROM_TEXT('POINT($userPostalCode)')) LIMIT 1";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // 输出最近的邮政编码位置信息
    while($row = $result->fetch_assoc()) {
        echo "最近的邮政编码位置是：" . $row["location"];
    }
} else {
    echo "未找到相关邮政编码位置信息";
}

$conn->close();
?>