PDO数据库操作类

 <?php
 include 'common_config.php';

 /**
  * Class Mysql
  * PDO数据库操作类
  */
 class Mysql {
     protected static $_dbh = null; //静态属性,所有数据库实例共用,避免重复连接数据库
     protected $_dbType = DB_TYPE;
     protected $_pconnect = false; //是否使用长连接
     protected $_host = DB_HOST;
     protected $_port = DB_PORT;
     protected $_user = DB_USER;
     protected $_pass = DB_PWD;
     protected $_dbName = DB_NAME; //数据库名
     protected $_sql = true; //最后一条sql语句
     protected $_where = '';
     protected $_order = '';
     protected $_limit = '';
     protected $_field = '*';
     protected $_clear = 0; //状态，0表示查询条件干净，1表示查询条件污染
     protected $_trans = 0; //事务指令数

     /**
      * 初始化类
      * @param array $conf 数据库配置
      */
     public function __construct(array $conf){
         class_exists('PDO') or die("PDO: class not exists.");
         if(!empty($conf)){
             $this->_host = $conf['host'];
             $this->_port = $conf['port'];
             $this->_user = $conf['user'];
             $this->_pass = $conf['passwd'];
             $this->_dbName = $conf['dbname'];
         }
         //连接数据库
         if ( is_null(self::$_dbh) ) {
             $this->_connect();
         }
     }

     /**
      * 连接数据库的方法
      */
     protected function _connect() {
         $dsn =$this->_dbType.':host='.$this->_host.';port='.$this->_port.';dbname='.$this->_dbName;
         $options = $this->_pconnect ? array(PDO::ATTR_PERSISTENT=>true) : array();
         try {
             $dbh = new PDO($dsn, $this->_user, $this->_pass, $options);
             $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);  //设置如果sql语句执行错误则抛出异常，事务会自动回滚
             $dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, false); //禁用prepared statements的仿真效果(防SQL注入)
         } catch (PDOException $e) {
             die('Connection failed: ' . $e->getMessage());
         }
         $dbh->exec('SET NAMES utf8');
         self::$_dbh = $dbh;
     }

     /**
      * 字段和表名添加 `符号
      * 保证指令中使用关键字不出错 针对mysql
      * @param string $value
      * @return string
      */
     protected function _addChar($value) {
         if ('*'==$value || false!==strpos($value,'(') || false!==strpos($value,'.') || false!==strpos($value,'`')) {
             //如果包含* 或者 使用了sql方法 则不作处理
         } elseif (false === strpos($value,'`') ) {
             $value = '`'.trim($value).'`';
         }
         return $value;
     }

     /**
      * 取得数据表的字段信息
      * @param string $tbName 表名
      * @return array
      */
     protected function _tbFields($tbName) {
         $sql = 'SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME="'.$tbName.'" AND TABLE_SCHEMA="'.$this->_dbName.'"';
         $stmt = self::$_dbh->prepare($sql);
         $stmt->execute();
         $result = $stmt->fetchAll(PDO::FETCH_ASSOC);
         $ret = array();
         foreach ($result as $key=>$value) {
             $ret[$value['COLUMN_NAME']] = 1;
         }
         return $ret;
     }

     /**
      * 过滤并格式化数据表字段
      * @param string $tbName 数据表名
      * @param array $data POST提交数据
      * @return array $newdata
      */
     protected function _dataFormat($tbName,$data) {
         if (!is_array($data)) return array();
         $table_column = $this->_tbFields($tbName);
         $ret=array();
         foreach ($data as $key=>$val) {
             if (!is_scalar($val)) continue; //值不是标量则跳过
             if (array_key_exists($key,$table_column)) {
                 $key = $this->_addChar($key);
                 if (is_int($val)) {
                     $val = intval($val);
                 } elseif (is_float($val)) {
                     $val = floatval($val);
                 } elseif (preg_match('/^\(\w*(\+|\-|\*|\/)?\w*\)$/i', $val)) {
                     // 支持在字段的值里面直接使用其它字段 ,例如 (score+1) (name) 必须包含括号
                     $val = $val;
                 } elseif (is_string($val)) {
                     $val = '"'.addslashes($val).'"';
                 }
                 $ret[$key] = $val;
             }
         }
         return $ret;
     }

     /**
      * 执行查询 主要针对 SELECT, SHOW 等指令
      * @param string $sql sql指令
      * @return mixed
      */
     protected function _doQuery($sql='') {
         $this->_sql = $sql;
         $pdostmt = self::$_dbh->prepare($this->_sql); //prepare或者query 返回一个PDOStatement
         $pdostmt->execute();
         $result = $pdostmt->fetchAll(PDO::FETCH_ASSOC);
         return $result;
     }

     /**
      * 执行语句 针对 INSERT, UPDATE 以及DELETE,exec结果返回受影响的行数
      * @param string $sql sql指令
      * @return integer
      */
     protected function _doExec($sql='') {
         $this->_sql = $sql;
         return self::$_dbh->exec($this->_sql);
     }

     /**
      * 执行sql语句，自动判断进行查询或者执行操作
      * @param string $sql SQL指令
      * @return mixed
      */
     public function doSql($sql='') {
         $queryIps = 'INSERT|UPDATE|DELETE|REPLACE|CREATE|DROP|LOAD DATA|SELECT .* INTO|COPY|ALTER|GRANT|REVOKE|LOCK|UNLOCK';
         if (preg_match('/^\s*"?(' . $queryIps . ')\s+/i', $sql)) {
             return $this->_doExec($sql);
         }
         else {
             //查询操作
             return $this->_doQuery($sql);
         }
     }

     /**
      * 获取最近一次查询的sql语句
      * @return String 执行的SQL
      */
     public function getLastSql() {
         return $this->_sql;
     }

     /**
      * 插入方法
      * @param string $tbName 操作的数据表名
      * @param array $data 字段-值的一维数组
      * @return int 受影响的行数
      */
     public function insert($tbName,array $data){
         $data = $this->_dataFormat($tbName,$data);
         if (!$data) return;
         $sql = "insert into ".$tbName."(".implode(',',array_keys($data)).") values(".implode(',',array_values($data)).")";
         return $this->_doExec($sql);
     }

     /**
      * 删除方法
      * @param string $tbName 操作的数据表名
      * @return int 受影响的行数
      */
     public function delete($tbName) {
         //安全考虑,阻止全表删除
         if (!trim($this->_where)) return false;
         $sql = "delete from ".$tbName." ".$this->_where;
         $this->_clear = 1;
         $this->_clear();
         return $this->_doExec($sql);
     }

     /**
      * 更新函数
      * @param string $tbName 操作的数据表名
      * @param array $data 参数数组
      * @return int 受影响的行数
      */
     public function update($tbName,array $data) {
         //安全考虑,阻止全表更新
         if (!trim($this->_where)) return false;
         $data = $this->_dataFormat($tbName,$data);
         if (!$data) return;
         $valArr = '';
         foreach($data as $k=>$v){
             $valArr[] = $k.'='.$v;
         }
         $valStr = implode(',', $valArr);
         $sql = "update ".trim($tbName)." set ".trim($valStr)." ".trim($this->_where);
         return $this->_doExec($sql);
     }

     /**
      * 查询函数
      * @param string $tbName 操作的数据表名
      * @return array 结果集
      */
     public function select($tbName='') {
         $sql = "select ".trim($this->_field)." from ".$tbName." ".trim($this->_where)." ".trim($this->_order)." ".trim($this->_limit);
         $this->_clear = 1;
         $this->_clear();
         return $this->_doQuery(trim($sql));
     }

     /**
      * @param mixed $option 组合条件的二维数组，例：$option['field1'] = array(1,'=>','or')
      * @return $this
      */
     public function where($option) {
         if ($this->_clear>0) $this->_clear();
         $this->_where = ' where ';
         $logic = 'and';
         if (is_string($option)) {
             $this->_where .= $option;
         }
         elseif (is_array($option)) {
             foreach($option as $k=>$v) {
                 if (is_array($v)) {
                     $relative = isset($v[1]) ? $v[1] : '=';
                     $logic    = isset($v[2]) ? $v[2] : 'and';
                     $condition = ' ('.$this->_addChar($k).' '.$relative.' '.$v[0].') ';
                 }
                 else {
                     $logic = 'and';
                     $condition = ' ('.$this->_addChar($k).'='.$v.') ';
                 }
                 $this->_where .= isset($mark) ? $logic.$condition : $condition;
                 $mark = 1;
             }
         }
         return $this;
     }

     /**
      * 设置排序
      * @param mixed $option 排序条件数组 例:array('sort'=>'desc')
      * @return $this
      */
     public function order($option) {
         if ($this->_clear>0) $this->_clear();
         $this->_order = ' order by ';
         if (is_string($option)) {
             $this->_order .= $option;
         }
         elseif (is_array($option)) {
             foreach($option as $k=>$v){
                 $order = $this->_addChar($k).' '.$v;
                 $this->_order .= isset($mark) ? ','.$order : $order;
                 $mark = 1;
             }
         }
         return $this;
     }

     /**
      * 设置查询行数及页数
      * @param int $page pageSize不为空时为页数，否则为行数
      * @param int $pageSize 为空则函数设定取出行数，不为空则设定取出行数及页数
      * @return $this
      */
     public function limit($page,$pageSize=null) {
         if ($this->_clear>0) $this->_clear();
         if ($pageSize===null) {
             $this->_limit = "limit ".$page;
         }
         else {
             $pageval = intval( ($page - 1) * $pageSize);
             $this->_limit = "limit ".$pageval.",".$pageSize;
         }
         return $this;
     }

     /**
      * 设置查询字段
      * @param mixed $field 字段数组
      * @return $this
      */
     public function field($field){
         if ($this->_clear>0) $this->_clear();
         if (is_string($field)) {
             $field = explode(',', $field);
         }
         $nField = array_map(array($this,'_addChar'), $field);
         $this->_field = implode(',', $nField);
         return $this;
     }

     /**
      * 清理标记函数
      */
     protected function _clear() {
         $this->_where = '';
         $this->_order = '';
         $this->_limit = '';
         $this->_field = '*';
         $this->_clear = 0;
     }

     /**
      * 手动清理标记
      * @return $this
      */
     public function clearKey() {
         $this->_clear();
         return $this;
     }

     /**
      * 启动事务
      * @return void
      */
     public function startTrans() {
         //数据rollback 支持
         if ($this->_trans==0) self::$_dbh->beginTransaction();
         $this->_trans++;
         return;
     }

     /**
      * 用于非自动提交状态下面的查询提交
      * @return boolen
      */
     public function commit() {
         $result = true;
         if ($this->_trans>0) {
             $result = self::$_dbh->commit();
             $this->_trans = 0;
         }
         return $result;
     }

     /**
      * 事务回滚
      * @return boolen
      */
     public function rollback() {
         $result = true;
         if ($this->_trans>0) {
             $result = self::$_dbh->rollback();
             $this->_trans = 0;
         }
         return $result;
     }

     /**
      * 关闭连接
      * PHP 在脚本结束时会自动关闭连接。
      */
     public function close() {
         if (!is_null(self::$_dbh)) self::$_dbh = null;
     }

 }