PHP实现简单用户登录界面

<form action="connet.php" method="POST" >用户名：<input type = "text" name = "username"/> <br />密码：<input type = "password" name="password"/> <br />重复密码：<input type = "password" name="repassword"/><br /><input type = "submit" value = "提交"/></form>

<?phpif(trim($_POST['password'])!=trim($_POST['repassword'])){ exit('两次密码不一致，请返回上一页');}  //$_POST用户名和密码 $username = $_POST['username']; $password = $_POST['password']; //连接mysql $con = mysqli_connect('localhost','root',''); //验证mysql连接是否成功if(mysqli_errno($con)){ echo "连接mysql失败：".mysqli_error($con); exit;}//设置数据库字符集 mysqli_set_charset($con,'utf8'); //查看数据库emp mysqli_select_db($con,'emp'); //查看表sgbf用户名与密码和传输值是否相等 $sql = "select *from sgbf where username='$username' and password='$password'"; //result必需规定由 mysqli_query()、mysqli_store_result() 或 mysqli_use_result() 返回的结果集标识符。 $result = mysqli_query($conn,$sql); $num = mysqli_num_rows($result);// 函数返回结果集中行的数量 if($num){  echo '成功'; }else{ echo'失败'; } mysqli_close($con); ?>