PHP数据库连接

PHP连接Mysql方式

MySQLi extension ("i" 意为 improved)
PDO (PHP Data Objects)
PDO 应用在 12 种不同数据库中， MySQLi 只针对 MySQL 数据库。

phpinfo() 查看是否安装PDO

php代码

连接数据库

<?php
//MySQLi - 面向对象
$servername = "localhost";
$username = "root";
$password = "root";

// 创建连接
$conn = new mysqli($servername, $username, $password);

// 检测连接
if ($conn->connect_error) {
  die("连接失败: " . $conn->connect_error);
}
echo "连接成功";


//MySQLi - 面向过程
// 创建连接
$conn = mysqli_connect($servername, $username, $password);

// 检测连接
if (!$conn) {
  die("Connection failed: " . mysqli_connect_error());
}
echo "连接成功";

//PDO
try {
  $conn = new PDO("mysql:host=$servername;", $username, $password);
  echo "连接成功";
} catch (PDOException $e) {
  echo $e->getMessage();
}

/*关闭对象*/
//MySQLi - 面向对象
$conn->close();

//MySQLi - 面向过程
mysqli_close($conn);

//PDO
$conn = null;

PDO增删改查

<?php
$host = '127.0.0.1';
$db   = 'autumn';
$user = 'root';
$pass = 'root';
$charset = 'utf8mb4';

$dsn = "mysql:host=$host;dbname=$db;charset=$charset";
$options = [
  PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
  PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
  PDO::ATTR_EMULATE_PREPARES   => false,
];

try {
  $pdo = new PDO($dsn, $user, $pass, $options);
} catch (\PDOException $e) {
  throw new \PDOException($e->getMessage(), (int)$e->getCode());
}

// Create
function createUser($name) {
  global $pdo;
  $sql = "INSERT INTO user (name) VALUES (?)";
  $stmt= $pdo->prepare($sql);
  $stmt->execute([$name]);
  echo "User Created\n";
}

// Read
function getUser($id) {
  global $pdo;
  $sql = "SELECT * FROM user WHERE id = ?";
  $stmt = $pdo->prepare($sql);
  $stmt->execute([$id]);
  $user = $stmt->fetch();
  print_r($user);
}

// Update
function updateUser($id, $name) {
  global $pdo;
  $sql = "UPDATE user SET name = ? WHERE id = ?";
  $stmt= $pdo->prepare($sql);
  $stmt->execute([$name, $id]);
  echo "User Updated\n";
}

// Delete
function deleteUser($id) {
  global $pdo;
  $sql = "DELETE FROM user WHERE id = ?";
  $stmt= $pdo->prepare($sql);
  $stmt->execute([$id]);
  echo "User Deleted\n";
}

// 使用示例
createUser('John Doe');
getUser(1);
updateUser(1, 'Jane Doe');
deleteUser(1);
?>