mysql语句中的占位符

SELECT * FROM users WHERE id = ?;

// 创建数据库连接
$conn = new mysqli($servername, $username, $password, $dbname);

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

// 准备SQL语句
$stmt = $conn->prepare("SELECT * FROM users WHERE id = ?");

// 绑定参数
$stmt->bind_param("i", $userId);

// 设置参数值
$userId = 1;

// 执行查询
$stmt->execute();

// 获取结果
$result = $stmt->get_result();

// 处理结果
while ($row = $result->fetch_assoc()) {
    echo "ID: " . $row["id"]. " - Name: " . $row["name"]. "<br>";
}

// 关闭连接
$stmt->close();
$conn->close();