<?php/*****************************数据库访问类(MySQLi版)******************************/class MySQLiDb{    //数据库链接本身    private $link;    //最后一次执行的sql语句    private $sql;    //初始化类    public function __construct($hostname,$username,$password,$database){        $this->link=new mysqli($hostname,$username,$password,$database);        if(mysqli_connect_error()){            $errorInfo=‘Error:Could not make a database link (‘.                mysqli_connect_errno().‘)‘.mysqli_connect_error();            throw new ErrorException($errorInfo, 1);        }        $this->link->set_charset("utf8");    }    //获取插入后生成的ID    private function getLastId(){        return $this->link->insert_id;    }    //获取影响的行数    private function countAffected(){        return $this->link->affected_rows;    }    //将数组格式的条件组装成字符串    private function rewhere($where){        $str=‘‘;        foreach($where as $key=>$value){            if(!empty($str)){                $str.=‘ and ‘;            }            $rekey=$this->link->escape_string($key);            $revalue=$this->link->escape_string($value);            $str.=is_numeric($revalue)?"`$rekey`=$revalue":"`$rekey`=‘$revalue‘";        }        return $str;    }    public function create($table,$model){        $fields=‘‘;        $values=‘‘;        foreach ($model as $key => $value) {            if($fields){                $fields.=‘,‘;            }            $fields.="`$key`";            if($values){                $values.=‘,‘;            }            $values.=is_numeric($value)?$value:"‘".$this->link->escape_string($value)."‘";        }        $this->sql="INSERT INTO `$table`($fields) VALUES($values)";        echo $this->sql;        $this->link->query($this->sql);        return $this->link->insert_id;    }    public function modify($table,$model,$where){        $assins=‘‘;        $where=$this->rewhere($where);        foreach ($model as $key => $value) {            $rkey=$this->link->escape_string($key);            $rvalue=$this->link->escape_string($value);            if(!is_numeric($rvalue)){                $rvalue="‘".$rvalue."‘";            }            $assins.=$assins?",`$rkey`=$rvalue":"`$rkey`=$rvalue";        }        $this->sql="UPDATE `$table` SET $assins WHERE $where";        echo $this->sql;        $this->link->query($this->sql);    }    public function remove($table,$where){        $where=$this->rewhere($where);        $this->sql="DELETE FROM `$table` WHERE $where";        echo $this->sql;        $this->link->query($this->sql);    }    public function search($table,$where){        $where=$this->rewhere($where);        $this->sql="SELECT * FROM `$table` WHERE $where";        $this->link->query($this->sql);        $result=$this->link->query($this->sql);        return $result -> fetch_assoc();    }    public function unique($table,$where){        $where=$this->rewhere($where);        $this->sql="SELECT * FROM `$table` WHERE $where LIMIT 1";        $result=$this->link->query($this->sql);        return $result -> fetch_object();    }}