class Db_Mysql
{
  private $_options = array();
  private $db;
  private $statement;
  private $_fetchMode = 2;
  /**
   * 构造函数
   *
   * @param string $host
   * @param string $username
   * @param string $password
   * @param string $dbname
   * @param string $charset
   */
  private function __construct($host, $username, $password, $dbname, $charset)
  {
    //初始化数据连接
    try {
      $dns = 'mysql:dbname=' . $dbname . ';host=' . $host;
      $this->db = new PDO($dns, $username, $password, array(PDO::ATTR_PERSISTENT => true, PDO::ATTR_AUTOCOMMIT => 1));
      $this->db->query('SET NAMES ' . $charset);
    } catch (PDOException $e) {
      echo header("Content-type: text/html; charset=utf-8");
      echo 'pre />';
      echo 'b>Connection failed:/b>' . $e->getMessage();
      die;
    }
  }
  /**
   * 调用初始化MYSQL连接
   *
   * @param string $config
   * @return Aomp_Db_Mysql
   */
  static public function getInstance($config = '')
  {
    $host = $config->host;
    $username = $config->username;
    $password = $config->password;
    $dbname = $config->dbname;
    $charset = $config->charset;
    $db = new self($host, $username, $password, $dbname, $charset);
    return $db;
  }
  /**
   * 获取多条数据
   *
   * @param string $sql
   * @param array $bind
   * @param string $fetchMode
   * @return multitype:
   */
  public function fetchAll($sql, $bind = array(), $fetchMode = null)
  {
    if($fetchMode === NULL){
      $fetchMode = $this->_fetchMode;
    }
    $stmt = $this->query($sql, $bind);
    $res = $stmt->fetchAll($fetchMode);
    return $res;
  }
  /**
   * 获取单条数据
   *
   * @param string $sql
   * @param array $bind
   * @param string $fetchMode
   * @return mixed
   */
  public function fetchRow($sql, array $bind = array(), $fetchMode = null)
  {
    if ($fetchMode === null) {
      $fetchMode = $this->_fetchMode;
    }
    $stmt = $this->query($sql, $bind);
    $result = $stmt->fetch($fetchMode);
    return $result;
  }
  /**
   * 获取统计或者ID
   *
   * @param string $sql
   * @param array $bind
   * @return string
   */
  public function fetchOne($sql, array $bind = array())
  {
    $stmt = $this->query($sql, $bind);
    $res = $stmt->fetchColumn(0);
    return $res;
  }
  /**
   * 增加
   *
   * @param string $table
   * @param array $bind
   * @return number
   */
  public function insert($table, array $bind)
  {
    $cols = array();
    $vals = array();
    foreach ($bind as $k => $v) {
      $cols[] = '`' . $k . '`';
      $vals[] = ':' . $k;
      unset($bind[$k]);
      $bind[':' . $k] = $v;
    }
    $sql = 'INSERT INTO '
      . $table
      . ' (' . implode(',', $cols) . ') '
      . 'VALUES (' . implode(',', $vals) . ')';
    $stmt = $this->query($sql, $bind);
    $res = $stmt->rowCount();
    return $res;
  }
  /**
   * 删除
   *
   * @param string $table
   * @param string $where
   * @return boolean
   */
  public function delete($table, $where = '')
  {
    $where = $this->_whereExpr($where);
    $sql = 'DELETE FROM '
      . $table
      . ($where ? ' WHERE ' .$where : '');
    $stmt = $this->query($sql);
    $res = $stmt->rowCount();
    return $res;
  }
  /**
   * 修改
   *
   * @param string $table
   * @param array $bind
   * @param string $where
   * @return boolean
   */
  public function update($table, array $bind, $where = '')
  {
    $set = array();
    foreach ($bind as $k => $v) {
      $bind[':' . $k] = $v;
      $v = ':' . $k;
      $set[] = $k . ' = ' . $v;
      unset($bind[$k]);
    }
    $where = $this->_whereExpr($where);
    $sql = 'UPDATE '
      . $table
      . ' SET ' . implode(',', $set)
      . (($where) ? ' WHERE ' . $where : '');
    $stmt = $this->query($sql, $bind);
    $res = $stmt->rowCount();
    return $res;
  }
  /**
   * 获取新增ID
   *
   * @param string $tableName
   * @param string $primaryKey
   * @return string
   */
  public function lastInsertId()
  {
    return (string) $this->db->lastInsertId();
  }
  public function query($sql, $bind = array())
  {
    if(!is_array($bind)){
      $bind = array($bind);
    }
    $stmt = $this->prepare($sql);
    $stmt->execute($bind);
    $stmt->setFetchMode($this->_fetchMode);
    return $stmt;
  }
  public function prepare($sql = '')
  {
    if(empty($sql)){
      return false;
    }
    $this->statement = $this->db->prepare($sql);
    return $this->statement;
  }
  public function execute($param = '')
  {
    if(is_array($param)){
      try {
        return $this->statement->execute($param);
      } catch (Exception $e) {
        return $e->getMessage();
      }
    }else {
      try {
        return $this->statement->execute();
      } catch (Exception $e) {
        return $e->getMessage();
      }
    }
  }
  /**
   *
   * @param string $where
   * @return null|string
   */
  protected function _whereExpr($where)
  {
    if(empty($where)){
      return $where;
    }
    if(!is_array($where)){
      $where = array($where);
    }
    $where = implode(' AND ', $where);
    return $where;
  }
  /**
   * 关闭数据库操作
   */
  public function close()
  {
    $this->_db = null;
  }
}

db.type = 'mysql'
db.host = '127.0.0.1'
db.username = 'root'
db.password = '123456'
db.dbname = 'test'
db.charset = 'UTF8'

class TestController extends Yaf_Controller_Abstract
{
  public function indexAction()
  {
    $config = Yaf_Application::app()->getConfig()->db;
    $db = Db_Mysql::getInstance($config);
    $row = $db->fetchOne('select count(*) from `user`');
    print_r($row);die;
  }
}