PHP使用mysqli扩展库实现增删改查（面向对象版）

<?php
 //数据库操作类
  class DBUtil{
   private $host="localhost";
   private $username="root";
   private $password="123456";
   private $dbname="student";
   private $conn;
   public function DBUtil(){
     $this->conn=new mysqli($this->host, $this->username, $this->password,$this->dbname) or die($this->conn->connect_error);
    
   }
  //查询
   public function query($sql){
     $all= $this->conn->query($sql);
     return $all;
   }
  //插入,修改，删除
   public function otherOperate($sql){
      if($this->conn->query($sql)){
        if($this->conn->affected_rows>0){
           return "OK";
        }else{
           return "ERROOR";
        }
      }
   }
   public function close(){
     $this->conn->close();
   }
  }
?>

<?php
  require_once "MySQLUtil.php";
   /*$sql="select * from m_student";
   $util=new DBUtil();
   $result=$util->query($sql);
   while($row=$result->fetch_assoc()){
        echo "$row[stuName]"."</br>";
   }
   $result->free();
   $util->close();*/
   $sql="update m_student set stuName=‘杨幂‘ where id=3";
   $util=new DBUtil();
   $result=$util->otherOperate($sql);
   echo $result;
   $util->close();
?>