PHP基于单例模式实现的数据库操作基类

本文实例讲述了PHP基于单例模式实现的数据库操作基类。分享给大家供大家参考，具体如下：

配置文件：

    <?php
    $db = array(
        'host'=>'localhost',
        'user'=>'root',
        'password'=>'',
        'database'=>'test',
    )
    ?>

php 数据库基类：

    <?php
    class db {
      public $conn;
      public static $sql;
      public static $instance=null;
      private function __construct(){
        require_once('db.config.php');
        $this->conn = mysql_connect($db['host'],$db['user'],$db['password']);
        if(!mysql_select_db($db['database'],$this->conn)){
          echo "失败";
        };
        mysql_query('set names utf8',$this->conn);
      }
      public static function getInstance(){
        if(is_null(self::$instance)){
          self::$instance = new db;
        }
        return self::$instance;
      }
      /**
       * 查询数据库
       */
      public function select($table,$condition=array(),$field = array()){
        $where='';
        if(!empty($condition)){
          foreach($condition as $k=>$v){
            $where.=$k."='".$v."' and ";
          }
          $where='where '.$where .'1=1';
        }
        $fieldstr = '';
        if(!empty($field)){
          foreach($field as $k=>$v){
            $fieldstr.= $v.',';
          }
           $fieldstr = rtrim($fieldstr,',');
        }else{
          $fieldstr = '*';
        }
        self::$sql = "select {$fieldstr} from {$table} {$where}";
        $result=mysql_query(self::$sql,$this->conn);
        $resuleRow = array();
        $i = 0;
        while($row=mysql_fetch_assoc($result)){
          foreach($row as $k=>$v){
            $resuleRow[$i][$k] = $v;
          }
          $i++;
        }
        return $resuleRow;
      }
      /**
       * 添加一条记录
       */
       public function insert($table,$data){
        $values = '';
        $datas = '';
        foreach($data as $k=>$v){
          $values.=$k.',';
          $datas.="'$v'".',';
        }
        $values = rtrim($values,',');
        $datas  = rtrim($datas,',');
        self::$sql = "INSERT INTO {$table} ({$values}) VALUES ({$datas})";
        if(mysql_query(self::$sql)){
          return mysql_insert_id();
        }else{
          return false;
        };
       }
       /**
       * 修改一条记录
       */
      public function update($table,$data,$condition=array()){
        $where='';
        if(!empty($condition)){
          foreach($condition as $k=>$v){
            $where.=$k."='".$v."' and ";
          }
          $where='where '.$where .'1=1';
        }
        $updatastr = '';
        if(!empty($data)){
          foreach($data as $k=>$v){
            $updatastr.= $k."='".$v."',";
          }
          $updatastr = 'set '.rtrim($updatastr,',');
        }
        self::$sql = "update {$table} {$updatastr} {$where}";
        return mysql_query(self::$sql);
      }
      /**
       * 删除记录
       */
       public function delete($table,$condition){
        $where='';
        if(!empty($condition)){
          foreach($condition as $k=>$v){
            $where.=$k."='".$v."' and ";
          }
          $where='where '.$where .'1=1';
        }
        self::$sql = "delete from {$table} {$where}";
        return mysql_query(self::$sql);
       }
      public static function getLastSql(){
        echo self::$sql;
      }
    }
    $db = db::getInstance();
    //$list = $db->select('demo',array('name'=>'tom','password'=>'ds'),array('name','password'));
    //echo $db->insert('demo',array('name'=>'脚本之家','password'=>'123'));
    //echo $db->update('demo',array("name"=>'xxx',"password"=>'123'),array('id'=>1));
    echo $db->delete('demo',array('id'=>'2'));
    db::getLastSql();
    echo "<pre>";
    ?>

更多关于PHP操作数据库相关内容感兴趣的读者可查看本站专题：《php+mysql数据库操作入门教程》、《PHP基于pdo操作数据库技巧总结》及《php常见数据库操作技巧汇总》

希望本文所述对大家PHP程序设计有所帮助。