<?php
class Db {
       private $db;
       public function __construct($db) {
         $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
         $this->db = $db;
       }

       public function insert($table, $fields, $insertParams = null) {
         try {
           $result = null;
           $names = '';
           $vals = '';
           foreach ($fields as $name => $val) {
             if (isset($names[0])) {
               $names .= ', ';
               $vals .= ', ';
             }
             $names .= $name;
             $vals .= ':' . $name;
           }
           $ignore = isset($insertParams['ignore']) && $insertParams['ignore']? 'IGNORE': '';
           $sql = "INSERT $ignore INTO " . $table . ' (' . $names . ') VALUES (' . $vals . ')';
           $rs = $this->db->prepare($sql);
           foreach ($fields as $name => $val) {
             $rs->bindValue(':' . $name, $val);
           }
           if ($rs->execute()) {
             $result = $this->db->lastInsertId(null);
           }
           return $result;
         } catch(Exception $e) {
           $this->report($e);
         }
       }

       // Returns true/false
       public function update($table, $fields, $where, $params = null) {
         try {
           $sql = 'UPDATE ' . $table . ' SET ';
           $first = true;
           foreach (array_keys($fields) as $name) {
             if (!$first) {
               $first = false;
               $sql .= ', ';
             }
             $first = false;
             $sql .= $name . ' = :_' . $name;
           }
           if (!is_array($params)) {
             $params = array();
           }
           $sql .= ' WHERE ' . $where;
           $rs = $this->db->prepare($sql);
           foreach ($fields as $name => $val) {
             $params[':_' . $name] = $val;
           }
           $result = $rs->execute($params);
           return $result;
         } catch(Exception $e) {
           $this->report($e);
         }
       }

       public function queryValue($query, $params = null) {
         try {
           $result = null;
           $stmt = $this->db->prepare($query);
           if ($stmt->execute($params)) {
             $result = $stmt->fetchColumn();
             $stmt->closeCursor();
           }
           return $result;
         } catch(Exception $e) {
           $this->report($e);
         }
       }

       public function queryValues($query, $params = null) {
         try {
           $result = null;
           $stmt = $this->db->prepare($query);
           if ($stmt->execute($params)) {
             $result = array();
             while ($row = $stmt->fetch(PDO::FETCH_NUM)) {
               $result[] = $row[0];
             }
           }
           return $result;
         } catch(Exception $e) {
           $this->report($e);
         }
       }

       public function queryRow($query, $params = null, $fetchStyle = PDO::FETCH_ASSOC, $classname = null) {
         $rows = $this->queryRowOrRows(true, $query, $params, $fetchStyle, $classname);
         return $rows;
       }

       public function queryRows($query, $params = null, $fetchStyle = PDO::FETCH_ASSOC, $classname = null) {
         $rows = $this->queryRowOrRows(false, $query, $params, $fetchStyle, $classname);
         return $rows;
       }
           
       private function queryRowOrRows($singleRow, $query, $params = null, $fetchStyle = PDO::FETCH_ASSOC, $classname = null) {
         try {
           $result = null;
           $stmt = $this->db->prepare($query);
           if($classname) {
             $stmt->setFetchMode($fetchStyle, $classname);
           } else {
             $stmt->setFetchMode($fetchStyle);
           }
           if ($stmt->execute($params)) {
             $result = $singleRow? $stmt->fetch(): $stmt->fetchAll();
             $stmt->closeCursor();
           }
           return $result;
         } catch(Exception $e) {
           $this->report($e);
         }
       }
           
       public function quote($str) {
         return $this->db->quote($str);
       }
           
       public function quoteArray($arr) {
         $result = array();
         foreach ($arr as $val) {
             $result[] = $this->db->quote($val);
         }
         return $result;
       }

       public function quoteImplodeArray($arr) {
         return implode(',', $this->quoteArray($arr));
       }

       // returns true/false
       public function sql($query, $params = null) {
         try {
           $result = null;
           $stmt = $this->db->prepare($query);
           return $stmt->execute($params);
         } catch(Exception $e) {
           $this->report($e);
         }
       }
           
       private function report($e) {
         throw $e;
       }

}
?>

Обьявление данных $pdo = new PDO($dsn, $user, $password);
Подключение $db = new Db($pdo);
Выборка одного значения $count = $db->queryValue('SELECT COUNT(*) FROM users');
Выборка набора записей $users = $db->queryRows('SELECT * FROM users WHERE name LIKE ?', array('%username%'));
Выборка одной записи $user = $db->queryRow('SELECT * FROM users WHERE id=:id', array(':id' => 123));
Добавление записи (INSERT) и получение значения поля AUTO_INCREMENT<br>$newUserId = $db->insert('users', array('name' => 'NewUserName', 'password' => 'zzxxcc'));
Изменение записи (UPDATE) $db->update('users', array('name' => 'UpdatedName'), 'id=:id', array(':id' => $newUserId));