PHP を使用して MySQL にデータの追加、削除、変更、クエリ関数を実装する方法

$host = "localhost";
$username = "root";
$password = "password";
$database = "mydatabase";

$conn = mysqli_connect($host, $username, $password, $database);
if (!$conn) {
    die("连接数据库失败：" . mysqli_connect_error());
}

$name = "John Doe";
$email = "johndoe@example.com";
$phone = "1234567890";

$sql = "INSERT INTO users (name, email, phone) VALUES ('$name', '$email', '$phone')";
if (mysqli_query($conn, $sql)) {
    echo "成功插入数据";
} else {
    echo "插入数据失败：" . mysqli_error($conn);
}

$sql = "SELECT * FROM users";
$result = mysqli_query($conn, $sql);

if (mysqli_num_rows($result) > 0) {
    while ($row = mysqli_fetch_assoc($result)) {
        echo "姓名：" . $row['name'] . "，邮箱：" . $row['email'] . "，电话：" . $row['phone'] . "<br>";
    }
} else {
    echo "没有数据";
}

$id = 1;
$newPhone = "9876543210";

$sql = "UPDATE users SET phone='$newPhone' WHERE id=$id";
if (mysqli_query($conn, $sql)) {
    echo "成功更新数据";
} else {
    echo "更新数据失败：" . mysqli_error($conn);
}

$id = 1;

$sql = "DELETE FROM users WHERE id=$id";
if (mysqli_query($conn, $sql)) {
    echo "成功删除数据";
} else {
    echo "删除数据失败：" . mysqli_error($conn);
}