使用过ThinkPHP框架的同学可能会对于其中数据库模型操作特别有好感，ThinkPHP提供了数据库操作的简单的操作，对于连接数据库，数据库的增删改查等数据操作都非常的nice，同时支持连贯操作，对于那些不习惯写sql语句的同学真是大大的便利。(注：sql还是很重要的，不要因为用了框架就把原先的忘了)。
而在笔者使用php操作redis实现后台任务的过程中，也想要借助这种便利，但无奈redis操作单独的类，直接访问其中的controller文件的话，总是会提示M方法失败，导致此模型方法不能使用。万般无奈之下，只能自己来实现一下了。
借助PHP的mysqli相关函数，进行MySQL数据库操作类的实现。此程序中提供数据库的操作包括：数据库的连接，数据库的选择，数据库用户的选择，相应数据库中所有数据表名的查看；数据表的操作包括：相应的数据表中字段全部属性的查看，数据表的增删改查操作，数据表查询、插入的连贯操作等

_initialize();        if(!isset($host)||!isset($user)||!isset($passowrd)||!isset($database)){            return false;        }else{            $this->_host     = $host;            $this->_user     = $user;            $this->_password = $passowrd;            $this->_database = $database;            $this->_port     = $port;            $_dbObj = new mysqli($host,$user,$passowrd,$database,$port);            if($_dbObj->connect_errno){                $this->error = $_dbObj->connect_error;                return false;            }else{                $this->_dbObj = $_dbObj;                return $this;            }        }    }        public function error(){        return $this->error;    }    // 回调方法 初始化模型    protected function _initialize() {}        public function __set($name,$value) {        // 设置数据对象属性        $this->data[$name] = $value;    }        public function __get($name) {        return isset($this->data[$name])?$this->data[$name]:null;    }        public function __isset($name) {        return isset($this->data[$name]);    }        public function __unset($name) {        unset($this->data[$name]);    }        public function __call($method,$args) {            }        public function select_db($database){        $select_db = mysqli_select_db($this->_dbObj,$database);        if($select_db){            $this->_database = $database;            $_dbObj = new mysqli($this->_host,$this->_user,$this->_password,$database,$this->_port);            $this->_dbObj = $_dbObj;            return $this;        }else{            $this->error = mysqli_error($this->_dbObj);            return false;        }    }        public function change_user($user,$password){        $change_user = mysqli_change_user($this->_dbObj,$user,$password,$this->_database);        if($change_user){            $this->_user = $user;            $this->_password = $password;            $_dbObj = new mysqli($this->_host,$this->_user,$this->_password,$this->_database,$this->_port);            $this->_dbObj = $_dbObj;            return $this;        }else{            $this->error = mysqli_error($this->_dbObj);            return false;        }    }        public function tables(){        $sql = 'show tables';        $search_res = mysqli_query($this->_dbObj,$sql);        if($search_res){            $num_rows = $search_res->num_rows;            $tables_msg = array(                'count'=>$num_rows,                'tables'=>array()            );            for($i=0;$i<$num_rows;$i++){                $row = $search_res->fetch_assoc();                $key = 'Tables_in_'.$this->_database;                array_push($tables_msg['tables'],$row[$key]);            }            mysqli_free_result($search_res);            return $tables_msg;        }else{            mysqli_free_result($search_res);            return false;        }    }        public function select_table($table){        $sql = 'select * from '.$table;        $search_res = mysqli_query($this->_dbObj,$sql);        if($search_res){            $this->_table = $table;            $table_msg = self::query_handle($search_res);            $this->_tableObj = $table_msg;            mysqli_free_result($search_res);            return $table_msg;        }else{            mysqli_free_result($search_res);            return false;        }    }        public function select_table_fields($table){        $sql = 'show fields from '.$table;        $search_res = mysqli_query($this->_dbObj,$sql);        if($search_res){            $this->_table = $table;            $fields_msg = self::query_handle($search_res);            mysqli_free_result($search_res);            return $fields_msg;        }else{            mysqli_free_result($search_res);            return false;        }    }        public function getField($field){        $fields = self::param_handle($field);        $count = count($fields);        for($i=0;$i<$count;$i++){            $index = $fields[$i];            $sql = 'select '.$index.' from '.$this->_table;            $res = mysqli_query($this->_dbObj,$sql);            $field_msg[$index] = self::query_handle($res);        }        return $field_msg;    }        protected function query_handle($obj){        $res = array();        for($i=0;$i<$obj->num_rows;$i++){            $row = $obj->fetch_assoc();            array_push($res,$row);        }        return $res;    }        public function param_handle($param){        if(is_string($param)&&!empty($param)){            $params = explode(',',$param);        }elseif(is_array($param)&&!empty($param)){            $params = $param;        }else{            return false;        }        return $params;    }        public function options_handle($param){        if(is_numeric($param)){            $option = $param;        }elseif(is_string($param)&&!empty($param)&&!is_numeric($param)){            $params = explode(',',$param);            $count = count($params);            $option = implode(' and ',$params);        }elseif(is_array($param)&&!empty($param)){            $params = $param;            $count = count($params);            $arr = array();            foreach($param as $key=>$value){                $tip = "$key=$value ";                array_push($arr,$tip);            }            $option = implode(' and ',$arr);        }else{            return false;        }        return $option;    }        protected function option(){        $options = $this->options;        $option = '';        if(isset($options['where'])){            $option .= 'where '.$options['where'].' ';        }        if(isset($options['order'])){            $option .= 'order by '.$options['order'].' '.$options['order_type'].' ';        }        if(isset($options['limit'])){            $option .= 'limit '.$options['limit'];        }        return $option;    }        public function find(){        $option = self::option();        $sql = 'select * from '.$this->_table.' '.$option;        $search_res = mysqli_query($this->_dbObj,$sql);        $msg = self::query_handle($search_res);        return $msg;    }        public function where($where){        $this->options['where'] = self::options_handle($where);        return $this;    }        public function limit($limit){        $this->options['limit'] = self::options_handle($limit);        return $this;    }        public function order($order,$type='desc'){        $this->options['order'] = $order;        $this->options['order_type'] = $type;        return $this;    }        public function data(array $data){        $values = array();        $fields = array();        if(is_array($data)){            foreach($data as $key=>$value){                if(is_array($value)){       //二维数组                    $tip = 1;                    array_push($values,'('.implode(',',array_values($value)).')');                    array_push($fields,'('.implode(',',array_keys($value)).')');                }else{      //一维数组                    $tip = 0;                }            }        }else{            return false;        }        if(!$tip){            array_push($values,'('.implode(',',array_values($data)).')');            array_push($fields,'('.implode(',',array_keys($data)).')');        }        $this->data['fields'] = $fields[0];        $this->data['values'] = implode(',',$values);        return $this;    }        public function add(){        $fields = $this->data['fields'];        $values = $this->data['values'];        $sql = 'INSERT INTO '.$this->_table.$fields.'VALUES'.$values;        $res = mysqli_query($this->_dbObj,$sql);        return $res;    }        function save(array $data){        $tip = array();        if(is_array($data)){            foreach($data as $key=>$value){                array_push($tip,"$key=$value");            }        }else{            return false;        }        $set_msg = implode(',',$tip);        $sql = 'UPDATE '.$this->_table.' SET '.$set_msg.' WHERE '.$this->options['where'];        $res = mysqli_query($this->_dbObj,$sql);        return $res;    }        public function delete(){        $sql = 'DELETE FROM '.$this->_table.' WHERE '.$this->options['where'];        $res = mysqli_query($this->_dbObj,$sql);        return $res;    }        public function query($sql){        $search_res = mysqli_query($this->_dbObj,$sql);        return $search_res;    }        protected function sql(){            }        public function close(){        $close = mysqli_close($this->_dbObj);        if($close){            return true;        }else{            return false;        }    }    function __destruct(){        mysqli_close($this->_dbObj);    }}

操作示例：
首先实例化此类，其中需要输入host(数据库地址)、user(数据库用户)、password(数据库用户密码)、database(数据库名称)此四种信息，进行数据库的连接，然后即可调用select_table()方法，其中传入数据表名，从而设置对指定表的操作，从而即可利用连贯操作进行相应数据的增删改查。 其中参数基本均支持字符串和数组两种形式。

include '/classes/db.php';            $db = new \Database('localhost', 'root', '901230', 'weixin');            //$db = new \mysqli('localhost','root','901230','weixin');            //$db->select_db('visitor');            //dump($db->error());            //$db->change_user('helen','901230');            $table = 'zyd_fuweng_user';            //dump($db->select_table_fields($table));            //dump($db->error());            $db->select_table($table);            $param1 = '123';            $param2 = 'id>1,record>100';            $param3 = array(                                array('count' => 4, 'openid' => '456', 'record' => '500')            );            $param4 = array('count' => 4, 'openid' => '456', 'record' => '500');            //dump($db->where('id=4')->save($param4));            dump($db->where('count=4')->delete());            die;            dump($db->data($param3)->add());            dump(array_keys($param3));            dump(array_values($param3));            dump(implode(',', array_values($param3)));            dump(implode(',', array_keys($param3)));            dump($db->where($param2)->order('id')->limit(2)->find());            dump($db->options_handle($param1));            dump($db->options_handle($param2));            dump($db->options_handle($param3));            $array = array('id', 'count');            $num = '123';            if (is_string($num)) {                echo 'true';            }            dump($db->getField($array));            dump($db->select_table_fields($table));                                                die;            //            $table = 'zyd_fuweng_user';            //选择指定的数据库，并返回其中全部信息            $table_msg = $db->select_table($table);            //选择指定数据库，返回数据库的字段信息            $table_field_msg = $db->select_table_fields($table);            //条件搜索，传入条件均为数据            $where = array(                'id' => 1            );            $data = array(                'headimgurl' => 'helen.jpg'            );            dump($db->where($where)->field('field'));            dump($table);