Comment utiliser le PDO de PHP pour encapsuler des classes de base de données hautement exploitables

class DB { private $pdo; // pdo对象 public function __construct($host, $dbname, $username, $password) { $dsn = "mysql:host=$host;dbname=$dbname;charset=utf8mb4"; $options = array( PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC, ); $this->pdo = new PDO($dsn, $username, $password, $options); } public function query($sql, $params = []) { $stmt = $this->pdo->prepare($sql); $stmt->execute($params); return $stmt; } public function fetchAll($sql, $params = []) { $stmt = $this->query($sql, $params); return $stmt->fetchAll(); } public function fetch($sql, $params = []) { $stmt = $this->query($sql, $params); return $stmt->fetch(); } public function insert($table, $data) { $columns = implode(', ', array_keys($data)); $values = ':' . implode(', :', array_keys($data)); $sql = "INSERT INTO $table ($columns) VALUES ($values)"; $this->query($sql, $data); } public function update($table, $data, $where = []) { $set = ''; foreach ($data as $key => $value) { $set .= "$key = :$key, "; } $set = rtrim($set, ', '); $whereClause = ''; foreach ($where as $key => $value) { $whereClause .= "$key = :$key AND "; } $whereClause = rtrim($whereClause, ' AND '); $sql = "UPDATE $table SET $set WHERE $whereClause"; $this->query($sql, array_merge($data, $where)); } public function delete($table, $where) { $whereClause = ''; foreach ($where as $key => $value) { $whereClause .= "$key = :$key AND "; } $whereClause = rtrim($whereClause, ' AND '); $sql = "DELETE FROM $table WHERE $whereClause"; $this->query($sql, $where); } }

// 创建数据库实例 $db = new DB('localhost', 'mydatabase', 'username', 'password'); // 查询操作 $result = $db->fetchAll("SELECT * FROM users"); foreach ($result as $row) { echo $row['name']; } echo "
"; // 插入操作 $db->insert("users", [ 'name' => 'Tom', 'age' => 20 ]); // 更新操作 $db->update("users", [ 'age' => 21 ], [ 'name' => 'Tom' ]); // 删除操作 $db->delete("users", [ 'name' => 'Tom' ]);