如何使用php在html页面上显示消息

我正在做一个关于分数管理系统的项目。在这个项目中，我有一个任务是更新学生的分数。假设更新成功，我应该显示一条消息，说明它成功了，否则
应显示“未成功”。我正在用php和html做我的项目。代码如下。

$con=mysql_connect(DB_HOST,DB_USER,DB_PASSWORD) or die("Failed to connect to MySQL: " . mysql_error());
$db=mysql_select_db(DB_NAME,$con) or die("Failed to connect to MySQL: " . mysql_error());

function updatem()
{
    session_start();
        $marks=$_POST['marks'];
        $branch=$_POST['Branch'];
        $semester=$_POST['Semester'];
        $subject=$_POST['Subject'];
        $userid=$_POST['userid'];
        if((!empty($_POST['userid']))
        &&(!empty($_POST['marks']))
        &&(!empty($_POST['Subject']))
        &&(!empty($_POST['Semester']))
        &&(!empty($_POST['Branch'])))
        {
            $query=mysql_query("UPDATE marks_list SET marks_obt=$marks 
                                WHERE username_id=$userid 
        AND branch_id=(SELECT branch_id FROM branch WHERE branch_name='$branch') AND 
        semester_id=(SELECT semester_id FROM semester WHERE semester_name='$semester') 
        AND subject_code=(select subject_code FROM subcodes WHERE 
        branch_id=(SELECT branch_id FROM branch WHERE branch_name='$branch') 
        AND 
        semester_id=(SELECT semester_id FROM semester WHERE semester_name='$semester'))") or die("insertion unsuccessful".mysql_error());

        header("Location: update_marks.html");
        }


}

if(isset($_POST['submit']))
{
    updatem();
}
?>

更新标记

user_id: <input type="text" name="userid"><br>

Branch<select name="Branch">
<option value="cse">CSE</option>
<option value="eee">EEE</option>
<option value="ece">ECE</option>
</select>

Marks<br><input type="text" name="marks" size="40"></br>

<select name="Subject">
<optgroup label="CSE">
    <optgroup label="sem 4">
        <option value="dbms">DBMS</option>
</optgroup>
<optgroup label="EEE">
</optgroup>
<optgroup label="ECE">
</optgroup>
</select>

Semester<select name="Semester">
<option value="sem 1">SEM 1</option>
<option value="sem 2">SEM 2</option>
<option value="sem 3">SEM 3</option>
<option value="sem 4">SEM 4</option>
<option value="sem 5">SEM 5</option>
<option value="sem 6">SEM 6</option>
<option value="sem 7">SEM 7</option>
</select>

<input id="button" type="submit" name="submit" value="SUBMIT">
</form>
</body>
</html>

---

提前感谢。

在更新查询后添加此代码

user_id: <input type="text" name="userid"><br>

Branch<select name="Branch">
<option value="cse">CSE</option>
<option value="eee">EEE</option>
<option value="ece">ECE</option>
</select>

Marks<br><input type="text" name="marks" size="40"></br>

<select name="Subject">
<optgroup label="CSE">
    <optgroup label="sem 4">
        <option value="dbms">DBMS</option>
</optgroup>
<optgroup label="EEE">
</optgroup>
<optgroup label="ECE">
</optgroup>
</select>

Semester<select name="Semester">
<option value="sem 1">SEM 1</option>
<option value="sem 2">SEM 2</option>
<option value="sem 3">SEM 3</option>
<option value="sem 4">SEM 4</option>
<option value="sem 5">SEM 5</option>
<option value="sem 6">SEM 6</option>
<option value="sem 7">SEM 7</option>
</select>

<input id="button" type="submit" name="submit" value="SUBMIT">
</form>
</body>
</html>

$con=mysql_connect(DB_HOST,DB_USER,DB_PASSWORD) or die("Failed to connect to MySQL: " . mysql_error());
$db=mysql_select_db(DB_NAME,$con) or die("Failed to connect to MySQL: " . mysql_error());

function updatem()
{
    session_start();
        $marks=$_POST['marks'];
        $branch=$_POST['Branch'];
        $semester=$_POST['Semester'];
        $subject=$_POST['Subject'];
        $userid=$_POST['userid'];
        if((!empty($_POST['userid']))
        &&(!empty($_POST['marks']))
        &&(!empty($_POST['Subject']))
        &&(!empty($_POST['Semester']))
        &&(!empty($_POST['Branch'])))
        {
            $query=mysql_query("UPDATE marks_list SET marks_obt=$marks 
                                WHERE username_id=$userid 
        AND branch_id=(SELECT branch_id FROM branch WHERE branch_name='$branch') AND 
        semester_id=(SELECT semester_id FROM semester WHERE semester_name='$semester') 
        AND subject_code=(select subject_code FROM subcodes WHERE 
        branch_id=(SELECT branch_id FROM branch WHERE branch_name='$branch') 
        AND 
        semester_id=(SELECT semester_id FROM semester WHERE semester_name='$semester'))") or die("insertion unsuccessful".mysql_error());

        header("Location: update_marks.html");
        }


}

if(isset($_POST['submit']))
{
    updatem();
}
?>

if(mysql_affected_rows()>0)
 {
     $_SESSION['message']='This is your message';
 }

现在在要显示值的文件中

user_id: <input type="text" name="userid"><br>

Branch<select name="Branch">
<option value="cse">CSE</option>
<option value="eee">EEE</option>
<option value="ece">ECE</option>
</select>

Marks<br><input type="text" name="marks" size="40"></br>

<select name="Subject">
<optgroup label="CSE">
    <optgroup label="sem 4">
        <option value="dbms">DBMS</option>
</optgroup>
<optgroup label="EEE">
</optgroup>
<optgroup label="ECE">
</optgroup>
</select>

Semester<select name="Semester">
<option value="sem 1">SEM 1</option>
<option value="sem 2">SEM 2</option>
<option value="sem 3">SEM 3</option>
<option value="sem 4">SEM 4</option>
<option value="sem 5">SEM 5</option>
<option value="sem 6">SEM 6</option>
<option value="sem 7">SEM 7</option>
</select>

<input id="button" type="submit" name="submit" value="SUBMIT">
</form>
</body>
</html>

添加此代码

user_id: <input type="text" name="userid"><br>

Branch<select name="Branch">
<option value="cse">CSE</option>
<option value="eee">EEE</option>
<option value="ece">ECE</option>
</select>

Marks<br><input type="text" name="marks" size="40"></br>

<select name="Subject">
<optgroup label="CSE">
    <optgroup label="sem 4">
        <option value="dbms">DBMS</option>
</optgroup>
<optgroup label="EEE">
</optgroup>
<optgroup label="ECE">
</optgroup>
</select>

Semester<select name="Semester">
<option value="sem 1">SEM 1</option>
<option value="sem 2">SEM 2</option>
<option value="sem 3">SEM 3</option>
<option value="sem 4">SEM 4</option>
<option value="sem 5">SEM 5</option>
<option value="sem 6">SEM 6</option>
<option value="sem 7">SEM 7</option>
</select>

<input id="button" type="submit" name="submit" value="SUBMIT">
</form>
</body>
</html>

$con=mysql_connect(DB_HOST,DB_USER,DB_PASSWORD) or die("Failed to connect to MySQL: " . mysql_error());
$db=mysql_select_db(DB_NAME,$con) or die("Failed to connect to MySQL: " . mysql_error());

function updatem()
{
    session_start();
        $marks=$_POST['marks'];
        $branch=$_POST['Branch'];
        $semester=$_POST['Semester'];
        $subject=$_POST['Subject'];
        $userid=$_POST['userid'];
        if((!empty($_POST['userid']))
        &&(!empty($_POST['marks']))
        &&(!empty($_POST['Subject']))
        &&(!empty($_POST['Semester']))
        &&(!empty($_POST['Branch'])))
        {
            $query=mysql_query("UPDATE marks_list SET marks_obt=$marks 
                                WHERE username_id=$userid 
        AND branch_id=(SELECT branch_id FROM branch WHERE branch_name='$branch') AND 
        semester_id=(SELECT semester_id FROM semester WHERE semester_name='$semester') 
        AND subject_code=(select subject_code FROM subcodes WHERE 
        branch_id=(SELECT branch_id FROM branch WHERE branch_name='$branch') 
        AND 
        semester_id=(SELECT semester_id FROM semester WHERE semester_name='$semester'))") or die("insertion unsuccessful".mysql_error());

        header("Location: update_marks.html");
        }


}

if(isset($_POST['submit']))
{
    updatem();
}
?>

重要提示：始终在页面顶部开始会话

user_id: <input type="text" name="userid"><br>

Branch<select name="Branch">
<option value="cse">CSE</option>
<option value="eee">EEE</option>
<option value="ece">ECE</option>
</select>

Marks<br><input type="text" name="marks" size="40"></br>

<select name="Subject">
<optgroup label="CSE">
    <optgroup label="sem 4">
        <option value="dbms">DBMS</option>
</optgroup>
<optgroup label="EEE">
</optgroup>
<optgroup label="ECE">
</optgroup>
</select>

Semester<select name="Semester">
<option value="sem 1">SEM 1</option>
<option value="sem 2">SEM 2</option>
<option value="sem 3">SEM 3</option>
<option value="sem 4">SEM 4</option>
<option value="sem 5">SEM 5</option>
<option value="sem 6">SEM 6</option>
<option value="sem 7">SEM 7</option>
</select>

<input id="button" type="submit" name="submit" value="SUBMIT">
</form>
</body>
</html>

session_start();

 echo $_SESSION['message'];

---

您的查询工作正常。然后将值存储在会话中。比你能显示的还要多。谢谢我的查询工作正常，标记正在更新。你能给我举个例子，通过变量显示更新成功的消息吗？谢谢，请看答案。让我知道，谢谢你的问题很糟糕。。而且你的代码根本不安全，因为它对sql的开放性很强injection@NullPoi我知道，但这是我的小型项目，我正处于开发的开始阶段，我想稍后再处理安全问题。。。但是，如果你想帮助或建议某事，它会被衷心接受。

$con=mysql_connect(DB_HOST,DB_USER,DB_PASSWORD) or die("Failed to connect to MySQL: " . mysql_error());
$db=mysql_select_db(DB_NAME,$con) or die("Failed to connect to MySQL: " . mysql_error());

function updatem()
{
    session_start();
        $marks=$_POST['marks'];
        $branch=$_POST['Branch'];
        $semester=$_POST['Semester'];
        $subject=$_POST['Subject'];
        $userid=$_POST['userid'];
        if((!empty($_POST['userid']))
        &&(!empty($_POST['marks']))
        &&(!empty($_POST['Subject']))
        &&(!empty($_POST['Semester']))
        &&(!empty($_POST['Branch'])))
        {
            $query=mysql_query("UPDATE marks_list SET marks_obt=$marks 
                                WHERE username_id=$userid 
        AND branch_id=(SELECT branch_id FROM branch WHERE branch_name='$branch') AND 
        semester_id=(SELECT semester_id FROM semester WHERE semester_name='$semester') 
        AND subject_code=(select subject_code FROM subcodes WHERE 
        branch_id=(SELECT branch_id FROM branch WHERE branch_name='$branch') 
        AND 
        semester_id=(SELECT semester_id FROM semester WHERE semester_name='$semester'))") or die("insertion unsuccessful".mysql_error());

        header("Location: update_marks.html");
        }


}

if(isset($_POST['submit']))
{
    updatem();
}
?>