戳到爆的DB类。。只为记录自己的历程。PHP

<?php
    class Db{
        private $_link    = '';      //设置连接信息
        private $_db_host = '';      //数据库服务器主机
        private $_db_user = '';      //数据库用户
        private $_db_pwd  = '';      //数据库密码
        private $_db_name = '';      //所使用数据库的名字
        private $_db_charset = '';   //设置字符集
        private $_query   = '';    //当前sql指令
        private $_table_name  = '';  //设置数据表
        private $_table_prefix = ''; //数据表的前缀
        private $_where   = '';       //设置where条件
        private $_order   = '';      //设置排序条件
        private $_field   = '';      //设置选择区域
        private $_limit   = '';      //设置limit条件
        private $_result  = '';      //需要返回的结果
        private $_fields  = '';      //设置操作内容

        function __construct($info_data){
            if(!is_array($info_data)) exit('请以关联数据的形式设置实例化Db');
            $this->_db_host = $info_data['db_host'];
            $this->_db_name = $info_data['db_name'];
            $this->_db_user = $info_data['db_user'];
            $this->_db_pwd  = $info_data['db_pwd'];
            $this->_db_charset = $info_data['db_charset'];
            $this->_table_prefix = $info_data['table_prefix'];
            //数据库连接
            $this->_link = @mysql_connect($this->_db_host,$this->_db_user,$this->_db_pwd) or die('数据库连接失败');
            //设置活动的数据库
            @mysql_select_db($this->_db_name);
            //设置输出字符集
            @mysql_query('set names ' . $this->_db_charset);
            return $this;
        }

        /*设置需要操作的tableName*/
        public function tablename($tableName){
            if(!empty($tableName)){
                $this->_table_name = $tableName;
            }
            return $this;
        }

        /*设置where*/
        public function where($where = ''){
            if(!empty($where)){
                $this->_where = ' where ' . $where;
            }
            return $this;
        }

        /*设置排序*/
        public function order($order = ''){
            if(!empty($order)){
                $this->_order = ' order by '.$order;
            }
            return $this;
        }

        /*设置field条件*/
        public function field($field = ''){
            if(!empty($field)){
                //进行重复过滤
                $opeField = array_unique(explode(',', $field));
                $field = ' `' . implode('`,`', $opeField) . '` ';
                $this->_fields = $field;
            }else{
                $this->_fields = ' * ';
            }
            return $this;
        }

        /*设置limit条件*/
        public function limit($limit = ''){
            if(!empty($limit)){
                if(is_numeric($limit)){
                    $this->_limit = ' limit 0,' . $limit . ' ';
                }else{
                    $this->_limit = ' limit ' . $limit;  
                }
            }
            return $this;
        }

        /*增加*/
        public function add($data){
            if(!empty($data)){
                $str = ' set ';
                foreach ($data as $key => $value) {
                    $str .= "$key=$value,";
                }
                $str = rtrim($str,',');
                $this->_query = mysql_query("insert into ".$this->_table_prefix.$this->_table_name.$str);
                if($this->_query){
                    return true;
                }else{
                    return false;
                }
            }
        }

        /*find查找一条数据*/
        public function find(){
            $fields = empty($fields)? ' * ' : $this->_fields;
            $this->_query = mysql_query('select '.$fields.' from '.$this->_table_prefix.$this->_table_name.$this->_where.$this->_order.$this->_limit);
            if(is_resource($this->_query)){
                $result = mysql_fetch_assoc($this->_query);
                if(!empty($result)){
                    return $result;
                }
            }
            //释放内存
            mysql_free_result($this->_query);
        }

        /*findAll查找多行数据*/
        public function findAll(){
            $fields = empty($fields)? ' * ' : $this->_fields;
            $this->_query = mysql_query('select'.$fields.' from '.$this->_table_prefix.$this->_table_name.$this->_where.$this->_order.$this->_limit);
            if(is_resource($this->_query)){
                $resultData = array();
                while($result = mysql_fetch_assoc($this->_query)){
                    $resultData[] = $result;
                }
                return $resultData;
            }
            //释放内存
            mysql_free_result($this->_query);
        }

        /*select*/
        public function select(){
            $fields = empty($fields)? ' * ' : $this->_fields;
            $this->_query = mysql_query('select'.$fields.' from '.$this->_table_prefix.$this->_table_name.$this->_where.$this->_order.$this->_limit);
            if(is_resource($this->_query)){
                $resultData = array();
                while($result = mysql_fetch_assoc($this->_query)){
                    $resultData[] = $result;
                }
                return $resultData;
            }
            //释放内存
            mysql_free_result($this->_query);
        }

        /*根据where中的条件进行删除*/
        public function delete(){
            $this->_query = mysql_query("delete from ".$this->_table_prefix.$this->_table_name.$this->_where);
            if($this->_query){
                return true;
            }else{
                return false;
            }
            mysql_free_result($this->_query);
        }

        /*根据where中的条件来进行更新*/
        public function update($data){
            if(!empty($data)){
                $str = 'update `'.$this->_table_prefix.$this->_table_name.'` set ';
                foreach ($data as $key => $value) {
                     $str .= "`$key`='".$value."',";
                } 
                $str = rtrim($str,',');
                $str .= '  '.$this->_where;
                $this->_query = mysql_query($str);
                if($this->_query){
                    return true;
                }else{
                    return false;
                }
            }
            mysql_free_result($this->_query);
        }

        /*关闭数据库*/
        function __destruct(){
            mysql_close($this->_link);
        }
    }

?>