我想在提交表单后将输入的数据保留在表单的文本框中。我只对第一个文本框执行此操作以测试功能“VALUE =”“”但是当我填写文本框并提交表单时，文本框中会出现通知错误“
注意: undefined variable :/web/stud/u0867587/MOBILEPHP/exam_interface.php 中 13
行的 sessionid。当我在互联网上查看如何正确执行时，所有州都按照我的方式执行。那么为什么它不起作用，你能帮我解决这个问题吗？
代码如下:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Exam Interface</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
</head>
<body>
<p><strong>NOTE: </strong>If a search box is left blank, then the form will search for all data under that specific field</p>
<form action="exam_interface.php" method="post" name="sessionform"> <!-- This will post the form to its own page"-->
<p>Session ID: <input type="text" name="sessionid" value="<?PHP print $sessionid ; ?>" /></p> <!-- Enter Session Id here-->
<p>Module Number: <input type="text" name="moduleid" /></p> <!-- Enter Module Id here-->
<p>Teacher Username: <input type="text" name="teacherid" /></p> <!-- Enter Teacher here-->
<p>Student Username: <input type="text" name="studentid" /></p> <!-- Enter User Id here-->
<p>Grade: <input type="text" name="grade" /></p> <!-- Enter Grade here-->
<p>Order Results By: <select name="order">
<option value="ordersessionid">Session ID</option>
<option value="ordermoduleid">Module Number</option>
<option value="orderteacherid">Teacher Username</option>
<option value="orderstudentid">Student Username</option>
<option value="ordergrade">Grade</option>
</select>
<p><input type="submit" value="Submit" name="submit" /></p>
</form>
<?php
$username="xxx";
$password="xxx";
$database="mobile_app";
mysql_connect('localhost',$username,$password);
@mysql_select_db($database) or die("Unable to select database");
if(isset($_POST['submit'])) {
$sessionid = isset ($_POST['sessionid']) ? $_POST['sessionid'] : "";
$moduleid = isset ($_POST['moduleid']) ? $_POST['moduleid'] : "";
$teacherid = isset ($_POST['teacherid']) ? $_POST['teacherid'] : "";
$studentid = isset ($_POST['studentid']) ? $_POST['studentid'] : "";
$grade = isset ($_POST['grade']) ? $_POST['grade'] : "";
$orderfield = isset ($_POST['order']) ? $_POST['order'] : "";
$sessionid = mysql_real_escape_string($sessionid);
$moduleid = mysql_real_escape_string($moduleid);
$teacherid = mysql_real_escape_string($teacherid);
$studentid = mysql_real_escape_string($studentid);
$grade = mysql_real_escape_string($grade);
?>
</body>
</html>
请帮忙，谢谢。
最佳答案
您正在使用 $sessionid before 检索它。将您的 php 指令放在 html 部分之前。
关于php - 在php中提交表单后，如何在文本框中输入数据？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/7778839/