php中PDO方式实现数据库的增删改查

需要开启php的pdo支持，php5.1以上版本支持

实现数据库连接单例化，有三要素 静态变量、静态实例化方法、私有构造函数 DPDO.php

class DPDO{  private $DSN;  private $DBUser;  private $DBPwd;  private $longLink;  private $pdo;  //私有构造函数 防止被直接实例化  private function __construct($dsn, $DBUser, $DBPwd, $longLink = false) {    $this->DSN = $dsn;    $this->DBUser = $DBUser;    $this->DBPwd = $DBPwd;    $this->longLink = $longLink;    $this->connect();  }  //私有 空克隆函数 防止被克隆  private function __clone(){}  //静态 实例化函数 返回一个pdo对象  static public function instance($dsn, $DBUser, $DBPwd, $longLink = false){    static $singleton = array();//静态函数 用于存储实例化对象    $singIndex = md5($dsn . $DBUser . $DBPwd . $longLink);    if (empty($singleton[$singIndex])) {      $singleton[$singIndex] = new self($dsn, $DBUser, $DBPwd, $longLink = false);    }    return $singleton[$singIndex]->pdo;  }     private function connect(){    try{      if($this->longLink){        $this->pdo = new PDO($this->DSN, $this->DBUser, $this->DBPwd, array(PDO::ATTR_PERSISTENT => true));      }else{        $this->pdo = new PDO($this->DSN, $this->DBUser, $this->DBPwd);      }      $this->pdo->query('SET NAMES UTF-8');    } catch(PDOException $e) {      die('Error:' . $e->getMessage() . '<br/>');    }  }}

用于处理字段映射，使用pdo的字段映射，可以有效避免sql注入

//字段关联数组处理， 主要用于写入和更新数据、同and 或 or 的查询条件，产生sql语句和映射字段的数组  public function FDFields($data, $link = ',', $judge = array(), $aliasTable = ''){    $sql = '';    $mapData = array();    foreach($data as $key => $value) {      $mapIndex = ':' . ($link != ',' ? 'c' : '') . $aliasTable . $key;      $sql .= ' ' . ($aliasTable ? $aliasTable . '.' : '') . '`' . $key . '` ' . ($judge[$key] ? $judge[$key] : '=') . ' ' . $mapIndex . ' ' . $link;      $mapData[$mapIndex] = $value;    }    $sql = trim($sql, $link);    return array($sql, $mapData);  }  //用于处理单个字段处理  public function FDField($field, $value, $judge = '=', $preMap = 'cn', $aliasTable = '') {    $mapIndex = ':' . $preMap . $aliasTable . $field;    $sql = ' ' . ($aliasTable ? $aliasTable . '.' : '') . '`' . $field . '`' . $judge . $mapIndex;    $mapData[$mapIndex] = $value;    return array($sql, $mapData);  }  //使用刚方法可以便捷产生查询条件及对应数据数组  public function FDCondition($condition, $mapData) {    if(is_string($condition)) {        $where = $condition;    } else if (is_array($condition)) {      if($condition['str']) {        if (is_string($condition['str'])) {          $where = $condition['str'];        } else {          return false;        }      }      if(is_array($condition['data'])) {        $link = $condition['link'] ? $condition['link'] : 'and';        list($conSql, $mapConData) = $this->FDFields($condition['data'], $link, $condition['judge']);        if ($conSql) {          $where .= ($where ? ' ' . $link : '') . $conSql;          $mapData = array_merge($mapData, $mapConData);        }      }    }    return array($where, $mapData);  }