如何在 html 页面上的任意位置显示 php 错误消息？

Question

默认情况下，mysqli_error 将在页面顶部显示第一个内容。

我正在尝试了解如何在页面上任意位置回显错误。

signup.php

if(isset($_POST['register'])){


    $username = $db->real_escape_string(trim(strip_tags($_POST['username'])));
    $checkrow = mysqli_query($db, "SELECT * FROM users WHERE username='".$username."'");

    if(mysqli_num_rows($checkrow) > 0){


        echo '<divclass="alert alert-danger">Username already exists. Please choose a different one</div>';

    }else{
//do some
}}


<html>
<body>
<div class="error_message"> Display error message here instead </div>
<form> Please sign up</form>
</body>
</html>

Answer 1

像这样：-

<?php
$error = '';//empty variable
if(isset($_POST['register'])){
    $username = $db->real_escape_string(trim(strip_tags($_POST['username'])));
    $checkrow = mysqli_query($db, "SELECT * FROM users WHERE username='".$username."'");

    if(mysqli_num_rows($checkrow) > 0){
       $error = 'Username already exists. Please choose a different one'; // assign error
    }else{
      //do some
    }
}
?>

<html>
<body>
<?php if(!empty($error)){?>
    <div class="error_message"><?php echo $error; // echo errors?></div>
<?php } ?>
<form> Please sign up</form>
</body>
</html>

注意：- 尝试阅读 prepared statements 并使用它们来防止 SQL Injection。谢谢

如何在 html 页面上的任意位置显示 php 错误消息？

How to display php error messages wherever I want on a html page?

php

mysqli

prepared-statement

flash-message