/**

• 构造
• @return MyPDO
  */
  private function __construct($dbHost,$dbUser,$dbPasswd,$dbName,$dbCharset)
  {
  try {
  $this->dsn = 'MysqL:host='.$dbHost.';dbname='.$dbName;
  $this->dbh = new PDO($this->dsn,$dbPasswd);
  $this->dbh->exec('SET character_set_connection='.$dbCharset.',character_set_results='.$dbCharset.',character_set_client=binary');
  } catch (PDOException $e) {
  $this->outputError($e->getMessage());
  }
  }

/**

• 防止克隆

• */
  private function __clone() {}

/**

• Singleton instance
• @return Object
  */
  public static function getInstance($dbHost,$dbCharset)
  {
  if (self::$_instance === null) {
  self::$_instance = new self($dbHost,$dbCharset);
  }
  return self::$_instance;
  }

/**

• Query 查询
• @param String $strsql sql语句
• @param String $queryMode 查询方式(All or Row)
• @param Boolean $debug
• @return Array
  */
  public function query($strsql,$queryMode = 'All',$debug = false)
  {
  if ($debug === true) $this->debug($strsql);
  $recordset = $this->dbh->query($strsql);
  $this->getPDOError();
  if ($recordset) {
  $recordset->setFetchMode(PDO::FETCH_ASSOC);
  if ($queryMode == 'All') {
  $result = $recordset->fetchAll();
  } elseif ($queryMode == 'Row') {
  $result = $recordset->fetch();
  }
  } else {
  $result = null;
  }
  return $result;
  }

/**

• Update 更新
• @param String $table 表名
• @param Array $arrayDataValue 字段与值
• @param String $where 条件
• @param Boolean $debug
• @return Int
  */
  public function update($table,$arrayDataValue,$where = '',$debug = false)
  {
  $this->checkFields($table,$arrayDataValue);
  if ($where) {
  $strsql = '';
  foreach ($arrayDataValue as $key => $value) {
  $strsql .= ",$key='$value'";
  }
  $strsql = substr($strsql,1);
  $strsql = "UPDATE $table SET $strsql WHERE $where";
  } else {
  $strsql = "REPLACE INTO $table (".implode(',',array_keys($arrayDataValue)).") VALUES ('".implode("','",$arrayDataValue)."')";
  }
  if ($debug === true) $this->debug($strsql);
  $result = $this->dbh->exec($strsql);
  $this->getPDOError();
  return $result;
  }

/**

• Insert 插入
• @param String $table 表名
• @param Array $arrayDataValue 字段与值
• @param Boolean $debug
• @return Int
  */
  public function insert($table,$arrayDataValue);
  $strsql = "INSERT INTO $table (".implode(',$arrayDataValue)."')";
  if ($debug === true) $this->debug($strsql);
  $result = $this->dbh->exec($strsql);
  $this->getPDOError();
  return $result;
  }

/**

• Replace 覆盖方式插入
• @param String $table 表名
• @param Array $arrayDataValue 字段与值
• @param Boolean $debug
• @return Int
  */
  public function replace($table,$arrayDataValue);
  $strsql = "REPLACE INTO $table(".implode(',$arrayDataValue)."')";
  if ($debug === true) $this->debug($strsql);
  $result = $this->dbh->exec($strsql);
  $this->getPDOError();
  return $result;
  }

/**

• Delete 删除
• @param String $table 表名
• @param String $where 条件
• @param Boolean $debug
• @return Int
  */
  public function delete($table,$debug = false)
  {
  if ($where == '') {
  $this->outputError("'WHERE' is Null");
  } else {
  $strsql = "DELETE FROM $table WHERE $where";
  if ($debug === true) $this->debug($strsql);
  $result = $this->dbh->exec($strsql);
  $this->getPDOError();
  return $result;
  }
  }

/**

• execsql 执行sql语句
• @param String $strsql
• @param Boolean $debug
• @return Int
  */
  public function execsql($strsql,$debug = false)
  {
  if ($debug === true) $this->debug($strsql);
  $result = $this->dbh->exec($strsql);
  $this->getPDOError();
  return $result;
  }

/**

• 获取字段最大值
• @param string $table 表名
• @param string $field_name 字段名
• @param string $where 条件
  */
  public function getMaxValue($table,$field_name,$debug = false)
  {
  $strsql = "SELECT MAX(".$field_name.") AS MAX_VALUE FROM $table";
  if ($where != '') $strsql .= " WHERE $where";
  if ($debug === true) $this->debug($strsql);
  $arrTemp = $this->query($strsql,'Row');
  $maxValue = $arrTemp["MAX_VALUE"];
  if ($maxValue == "" || $maxValue == null) {
  $maxValue = 0;
  }
  return $maxValue;
  }

/**

• 获取指定列的数量
• @param string $table
• @param string $field_name
• @param string $where
• @param bool $debug
• @return int
  */
  public function getCount($table,$debug = false)
  {
  $strsql = "SELECT COUNT($field_name) AS NUM FROM $table";
  if ($where != '') $strsql .= " WHERE $where";
  if ($debug === true) $this->debug($strsql);
  $arrTemp = $this->query($strsql,'Row');
  return $arrTemp['NUM'];
  }

/**

• 获取表引擎
• @param String $dbName 库名
• @param String $tableName 表名
• @param Boolean $debug
• @return String
  */
  public function getTableEngine($dbName,$tableName)
  {
  $strsql = "SHOW TABLE STATUS FROM $dbName WHERE Name='".$tableName."'";
  $arrayTableInfo = $this->query($strsql);
  $this->getPDOError();
  return $arrayTableInfo[0]['Engine'];
  }

/**

• beginTransaction 事务开始
  */
  private function beginTransaction()
  {
  $this->dbh->beginTransaction();
  }

/**

• commit 事务提交
  */
  private function commit()
  {
  $this->dbh->commit();
  }

/**

• rollback 事务回滚
  */
  private function rollback()
  {
  $this->dbh->rollback();
  }

/**

• transaction 通过事务处理多条sql语句
• 调用前需通过getTableEngine判断表引擎是否支持事务
• @param array $arraysql
• @return Boolean
  */
  public function execTransaction($arraysql)
  {
  $retval = 1;
  $this->beginTransaction();
  foreach ($arraysql as $strsql) {
  if ($this->execsql($strsql) == 0) $retval = 0;
  }
  if ($retval == 0) {
  $this->rollback();
  return false;
  } else {
  $this->commit();
  return true;
  }
  }

/**

• checkFields 检查指定字段是否在指定数据表中存在
• @param String $table
• @param array $arrayField
  */
  private function checkFields($table,$arrayFields)
  {
  $fields = $this->getFields($table);
  foreach ($arrayFields as $key => $value) {
  if (!in_array($key,$fields)) {
  $this->outputError("Unknown column $key in field list.");
  }
  }
  }

/**

• getFields 获取指定数据表中的全部字段名
• @param String $table 表名
• @return array
  */
  private function getFields($table)
  {
  $fields = array();
  $recordset = $this->dbh->query("SHOW COLUMNS FROM $table");
  $this->getPDOError();
  $recordset->setFetchMode(PDO::FETCH_ASSOC);
  $result = $recordset->fetchAll();
  foreach ($result as $rows) {
  $fields[] = $rows['Field'];
  }
  return $fields;
  }

/**

• getPDOError 捕获PDO错误信息
  */
  private function getPDOError()
  {
  if ($this->dbh->errorCode() != '00000') {
  $arrayError = $this->dbh->errorInfo();
  $this->outputError($arrayError[2]);
  }
  }

/**

• debug
• @param mixed $debuginfo
  */
  private function debug($debuginfo)
  {
  var_dump($debuginfo);
  exit();
  }

/**

• 输出错误信息
• @param String $strErrMsg
  */
  private function outputError($strErrMsg)
  {
  throw new Exception('MysqL Error: '.$strErrMsg);
  }

/**

• destruct 关闭数据库连接
  */
  public function destruct()
  {
  $this->dbh = null;
  }
  }
  ?>