单例模式实现简单的mysql操作类

单例模式实现简单的mysql操作类

为什么要弄个抽象类，原因是不清楚还会不会在代码基础上继续拓展。所以就先写上了。

代码：

抽象类：

<?php
    abstract class Mysql
    {
        abstract protected function connect();
        abstract protected function query($sql);
        abstract protected function err($sql='');
    }

操作类：

<?php
require_once('./Mysql.php');
    class db extends Mysql
    {
        private $config = array(
            'DB_HOST' => '127.0.0.1',   //主机
            'DB_USER' => 'root',        //用户名    
            'DB_PWD' => 'root',        //密码
            'DB_NAME' => 'test',        //数据库名
            'DB_CHARSET' => 'utf8',        //字符集
        );
        private $link;             //数据库连接标识;
        private $rows;             //查询获取的多行数组
        private $result;            //查询结果
        static $_instance; //存储对象

        private function __construct($config=array()){
            $this->config = $config ? $config : $this->config;
            $this->connect();
            
        }  

        //防止克隆
        private function __clone(){}

        //连接数据库
        public function connect()
        {
            $this->link = mysqli_connect($this->config['DB_HOST'],$this->config['DB_USER'],$this->config['DB_PWD']) or die(mysqli_connect_errno());
            mysqli_select_db($this->link,$this->config['DB_NAME']) or die(mysqli_error($this->link));
            $this->query("SET NAMES ".$this->config['DB_CHARSET']);
            return $this->link;
        }

        //查询数据
        public function query($sql) {
            $this->result = mysqli_query($this->link,$sql) or $this->err($sql);
            return $this->result;
        }

        protected function err($sql='')
        {
            echo '错误得sql语句'.$sql;
            exit;
        }

        //单例模式
        public static function getInstance(){
            if(FALSE == (self::$_instance instanceof self)){
                self::$_instance = new self();
            }
            return self::$_instance;
        }

        //查询单挑记录
        public function getRow($sql, $type = MYSQLI_ASSOC) {
            $result = $this->query($sql);
            return mysqli_fetch_array($result, $type);
        }

        /**
        * 多行记录
        */
        public function getRows($sql, $type = MYSQLI_ASSOC) {
            $result = $this->query($sql);
            while ($row = mysqli_fetch_array($result, $type)) {
            $this->rows[] = $row;
            }
            return $this->rows;
        }

        //插入数据
        public function insert($table,$data)
        {
            $str = '';
            $str .= "INSERT INTO `$table`";
            $str .= "(`".implode("`,`",array_keys($data))."`)";
            $str .= " VALUES ";
            $str .= "('".implode("','",$data)."')";
            $result = $this->query($str);
            if ($result && mysqli_affected_rows($this->link)>0) {
                return mysqli_insert_id($this->link);
            }else{
                return false;
            }
        }

        //插入数据
        public function update($table,$data,$where)
        {
            if (!$where) {
                die('条件不能为空');
            }
            $str = '';
            $str .= "UPDATE `$table` SET ";
            foreach ($data as $key => $value) {
                $str .='`'.$key.'`="'.$value.'",';
            }
            
            $str = rtrim($str,',');
            $str .= ' where '.$where;
            $result = $this->query($str);
            if ($result && mysqli_affected_rows($this->link)>0) {
                return mysqli_affected_rows($this->link);
            }else{
                return false;
            }
        }
        
        //删除数据
        public function delete($table,$where)
        {
            if (!$where) {
                die('条件不能为空');
            }
            $str = "DELETE FROM `$table` WHERE $where ";
            $result = $this->query($str);
            if ($result && mysqli_affected_rows($this->link)>0) {
                return mysqli_affected_rows($this->link);
            }else{
                return false;
            }
        }            

    }