PHP表单提交问题提问


html>

<html>

    <head>
        <meta charset="utf-8" />
        <title>register.phptitle>
        <link rel="stylesheet" type="text/css" href="css/register.css" />
    head>
    <body>
        <div class="register">
            <h2>注册h2>
            <form method="post" action=" echo htmlspecialchars($_SERVER['PHP_SELF']);?>"
            onsubmit="upload()">
                <div class="register_flex">
                    <div class="register_flex_box">
                        <input type="text" name="username" placeholder="请注册用户名" />
                    div>
                    <div class="register_flex_box">
                        <input type="password" name="password" placeholder="请自定义密码" />
                    div>
                    <div class="register_flex_box">
                        <input type="text" name="tip" placeholder="请自定义密保标题:" />
                    div>
                    <div class="register_flex_box">
                        <input type="text" name="tip_content" placeholder="请输入密保内容:" />
                    div>
                    <div class="register_flex_box">
                        <input class="register_button" type="submit" value="注册"/>
                    div>
                    <div class="register_flex_box">
                        <button class="register_button" name="register" onclick='window.open("04.php")'>登录button>
                    div>
                div>
            form>
        div>
        
        <script>
            function upload(){
                
                    $username=$password=$tip=$tip_content="";
                    if($_SERVER["REQUEST_METHOD"]=="POST"){
                        if (empty($_POST["username"])) {
                            echo "";
                        } else {
                            $name = check_input($_POST["name"]);
                        }
                        $username=check_input($_POST['username']);
                        $password=check_input($_POST['password']);
                        $tip=check_input($_POST['tip']);
                        $tip_content=check_input($_POST['tip_content']);
                    }
                    function check_input($data) {
                        $data = trim($data);
                        $data = stripslashes($data);
                        $data = htmlspecialchars($data);
                        return $data;
                    }
                    // 连接数据库
                    $con=mysqli_connect("localhost","test_connect_db","YNxb8Tj","test_connect_db");
                    if (!$con) 
                    { 
                        echo "连接 MySQL 失败: " . mysqli_connect_error(); 
                    }
                    $sql="insert into user (username,password,tip,tip_content) values ('$username','$password','$tip','$tip_content')";
                    if (mysqli_query($con, $sql)) {
                        echo "新记录插入成功";
                    } else {
                        echo "Error: " . $sql . "
"
. mysqli_error($con); } mysqli_close($con); ?>
} script> body>
html>

PHP提交表单出现一个问题,每次会提交两遍,哪个地方不对啊?

箭头位置的结束大括号放错位置,应该放到最后横线的位置

img

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