<?php
class sql{
public $conn;
public $host = "127.0.0.1";
public $uid = "root";
public $pwd = "";
public $db_name="cms";
public $sql;
//链接数据库
public function lianjie($conn){
$conn=mysqli_connect($this->host,$this->uid,$this->pwd,$this->db_name);
$this->conn=$conn;

}
public function getlianjie(){
    return $this->conn;

}

public function quer($sql){
    $sql="select * from user";
    $ret=mysqli_query($this->conn,$sql);
    $this->sql=$ret;
    }
public function getquer(){
    return $this->sql;
}

}
$ql=new sql();
$ces=$ql->getlianjie();
$ceshi=$ql->getlianjie();
$cesh=$ql->getquer();
var_dump($ceshi);
var_dump($cesh);