<?php     header("Content-type: text/html;charset=utf-8");     //mysqli操作mysql数据库(面向对象方式)     //1、创建MySQLi对象     $mysqli =new MySQLi("localhost","root","root","test");     if($mysqli->connect_error){         die("连接失败".$mysqli->connect_error);     }     //2、操作数据库（发送sql）     $sql="select *from user1";     //3、处理结果     $res =$mysqli->query($sql);     //var_dump($res);     //fetch_assoc \fetch_array \fetch_object     while($row=$res->fetch_row()){         var_dump($row); /*        foreach($row as $val){             echo '--'.$val;         }         echo '<br/>';*/     }     //4、关闭资源     $res->free();     $mysqli->close(); ?>

<?php     header("Content-type: text/html;charset=utf-8");     $mysqli=mysqli_connect("localhost","root","root","test");     if(!$mysqli){         die("连接失败".mysqli_connect_error());     }     $sql="select *from user1";     $res=mysqli_query($mysqli,$sql);     //var_dump($res);     while($row=mysqli_fetch_row($res)){         foreach ($row as $val){             echo '-'.$val;         }         echo '<br/>';     }     //释放内存     mysqli_free_result($res);     mysqli_close($mysqli); ?>

<?php     //使用mysqli 扩展库对mysql的crud 操作     header("Content-type: text/html;charset=utf-8");     $mysqli = new MySQLi("localhost","root","root","test");     if($mysqli->connect_error){         die("连接失败".$mysql->connect_error);     }     //增加一条记录     //$sql="insert into user1 (name,password,email,age) values ('lucy',md5('lucy'),'lucy@163.com',17)";     //删除一条记录     //$sql="delete from user1 where id =80";     //更新一条记录     $sql="update user1 set age=20 where id=7";     $res=$mysqli->query($sql);     if(!$res){         echo "操作失败".$mysqli->error;     }else{         if($mysqli->affected_rows>0){             echo "成功";         }else{             echo "没有行受影响";            }     }     //关闭资源     $mysqli->close(); ?>

<?     class SqlHelper{         private $mysqli;         //这里先写死，以后写死的东西用一个文件来配置         private static $host="localhost";         private static $user="root";         private static $pwd="root";         private static $db="test";         public function __construct(){             $this->mysqli=new MySQLi(self::$host,self::$user,self::$pwd,self::$db);             if($this->mysqli->connect_error){                 die("连接失败".$this->mysqli->connect_error);             }             //设置字符集             $this->mysqli->query("set names utf8");         }         //dql operate         function execute_dql($sql){             $res =$this->mysqli->query($sql) or die($this->mysqli->error);             return $res;                }         //dml operate         function execute_dml($sql){             $res =$this->mysqli->query($sql) or die($this->mysqli->error);             if(!$res){                 return 0;//失败             }else{                 if($this->mysqli->affected_rows>0){                     return 1;//成功                 }else{                     return 2;//没有行到影响                 }             }         }     } ?>