在PHP中 使用mysqli扩展库对mysql 的操作

1、在PHP中 使用mysqli扩展库对mysql 的dql操作

<?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();
?>

下面是面向过程的

<?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);
?>

2、在PHP中 使用mysqli扩展库对mysql 的dml操作

<?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();
?>

 3、进行封装 

<?

    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
                }
            }
        }
    }
?>