关于 PHP 与 MYSQL的链接

链接的语句 

                                                                 mysql主机             用户名     用户的密码    数据库的名字

                                                                                       地址

<?php                     ↑          ↑      ↑        ↑
$con = mysql_connect("localhost","peter","abc123","tast");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }

// some code

?> 
　　例子：

<?php
require_once 'application/view.php';
class LoginController {

    public function main($vars=array()){
        switch ($vars["action"]){
            case "loginAction":$this->loginAction($vars);break;//登录
        }
    }

    public function loginAction($vars=array()) {
        $userName = $vars["user_phone"];
        $userPassword = $vars["userPassword"];
                                            
       $con = mysqli_connect("localhost","root","","tast");    ""表示没有设置密码
       if( !$con ) {
           die('Could not connect: ' . mysql_error());
       }
       $ccc=array();
       $apple="select * from ppp;"; →  是MYSQL的查询语句
       $banana=mysqli_query($con,$apple);                  （$con是链接数据库的钥匙）
       while($row = mysqli_fetch_array($banana)){
//            var_dump($row);
           $ccc[]= $row;
       }
//        var_dump($a) ;
        $ASB=false;
       for ($i=0;$i<count($ccc);$i++){
            $a=$ccc[$i]["ppp_id"];
            $b=$ccc[$i]["ppp_title"];
//             var_dump($a);    测试函数的
//             var_dump($b);
            if($userName==$a){ 
                if($userPassword==$b){
                  $ASB=true;
                }
//                 else{
//                     $view = new View("/application/view/pc/login.php");
//                     echo "<script>alert('神知道你错了啥？')</script>";
// //                     $view->assign("info","请输入正确的用户名和密码");
//                 }
            } 
//             else{
//                 $view = new View("/application/view/pc/login.php");
//                 echo "请输入账号和密码！！";
//             }
       }
       if($ASB==false){ 
           if($userName==''){ 
               if($userPassword==''){
//                $view = new View("/application/view/pc/login.php");
               echo '<script language="javascript">alert("请注册账号！");window.history.back();</script>';
               exit();                                                          ↓
               }                                                            （非常好用，直接跳转到登录页面。）
              
           }if($userName==''){
               echo '<script language="javascript">alert("账号不能为空！");window.history.back();</script>';
               exit();
              
           }if($userPassword==''){
               echo '<script language="javascript">alert("密码不能为空！");window.history.back();</script>';
               
           }if($userName==$a){
               if($userPassword!=$b)
               {
               echo '<script language="javascript">alert("请输入正确密码！");window.history.back();</script>';
               exit();
               }
           }
           
       }else{
          echo"登录成功"; 
       }

    }
}
?>