Halaman log masuk pembangunan PHP Halaman PHP

<?php session_start(); header("Content-type:text/html;charset=utf-8"); $link = mysqli_connect('localhost','root','root','login'); //链接数据库 mysqli_set_charset($link ,'utf8'); //设定字符集 $name=$_POST['username']; $pwd=$_POST['password']; $yzm=$_POST['yzm']; //if($name==''){ // echo "<script>alert('请输入用户名');location='" . $_SERVER['HTTP_REFERER'] . "'</script>"; // exit; //} //if($pwd==''){ // // echo "<script>alert('请输入密码');location='" . $_SERVER['HTTP_REFERER'] . "'</script>"; // exit; // //} // //if($yzm!=$_SESSION['VCODE']){ // // echo"<script>alert('你的验证码不正确，请重新输入');location='".$_SERVER['HTTP_REFERER']. "'</script>"; // exit; // //} $sql_select="select id,username,password from user where username= ?"; //从数据库查询信息 $stmt=mysqli_prepare($link,$sql_select); mysqli_stmt_bind_param($stmt,'s',$name); mysqli_stmt_execute($stmt); $result=mysqli_stmt_get_result($stmt); $row=mysqli_fetch_assoc($result); if($row){ if($pwd !=$row['password'] || $name !=$row['username']){ echo "<script>alert('密码错误，请重新输入');location.href='login.html'</script>"; exit; } else{ $_SESSION['username']=$row['username']; $_SESSION['id']=$row['id']; echo "<script>alert('登录成功');location.href='first.html'</script>"; } }else{ echo "<script>alert('您输入的用户名不存在');location.href='login.html'</script>"; exit; };