PHP中的数据库相关数据类型及其操作示例

$username = 'John';
$password = '12345';
$content = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.';

$user_id = 1;
$age = 25;

$price = 9.99;
$latitude = 37.7749;
$longitude = -122.4194;

$is_logged_in = true;
$is_purchased = false;

$users = array('John', 'Mary', 'Tom');
$products = array('Apple' => 2.99, 'Banana' => 1.99, 'Orange' => 3.99);

class User {
    public $name;
    public $email;
  
    public function __construct($name, $email) {
        $this->name = $name;
        $this->email = $email;
    }
}

$user = new User('John', 'john@example.com');

$servername = "localhost";
$username = "root";
$password = "password";
$dbname = "my_database";

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

if ($conn->connect_error) {
    die("连接数据库失败：" . $conn->connect_error);
}

$sql = "INSERT INTO users (name, email) VALUES ('John', 'john@example.com')";

if ($conn->query($sql) === TRUE) {
    echo "数据插入成功";
} else {
    echo "数据插入失败：" . $conn->error;
}

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

if ($result->num_rows > 0) {
    while ($row = $result->fetch_assoc()) {
        echo "姓名：" . $row['name'] . "，邮箱：" . $row['email'] . "
";
    }
} else {
    echo "没有查询到数据";
}

$sql = "UPDATE users SET name = 'Mary' WHERE id = 1";

if ($conn->query($sql) === TRUE) {
    echo "数据更新成功";
} else {
    echo "数据更新失败：" . $conn->error;
}

$sql = "DELETE FROM users WHERE id = 1";

if ($conn->query($sql) === TRUE) {
    echo "数据删除成功";
} else {
    echo "数据删除失败：" . $conn->error;
}