Keep text value after submit - php

Question

I'm trying to find how to retain my text value after submit, so the text that i submit is still keep in the textbox, there's so many reference in internet but too hard for me to understand (newbie here), so i'd like to ask here, if anyone have some solution.
Here's my form code:
echo
"<form method='post' action='process.php'>
<tr>
<td>Nama Jurusan</td>
<td>:</td>
<td><input type='text' name='jurusan' size='50%'></td>
</tr>
<tr>
<td>Nama Laboratorium</td>
<td>:</td>
<td><input type='text' name='lab' size='50%></td>
</tr>
<input name='submit' type='submit' id='ajukan' value='Ajukan'>
</form>";
As you can see, i was placing the form inside echo.
Here's my process.php code:
<?php
if(isset($_REQUEST['submit'])) {
include "../conf/koneksi.php";
$jurusan = $_POST['jurusan'];
$lab = $_POST['lab'];
$urutkan= "ALTER TABLE tb_pengusul AUTO_INCREMENT = 1";
mysql_query($urutkan);
$input = mysql_query("INSERT INTO tb_pengusul (nama_jurusan,nama_laboratorium)
VALUES ('$jurusan','$lab')") or die (mysql_error());
echo "<script language=\"Javascript\">\n";
echo "window.alert('Input sukses !')";
echo "</script>";
echo "<META HTTP-EQUIV=\"REFRESH\" CONTENT=\"0;URL='../koordinator.php?url='\">";
}
?>

Answer 1

Use Post value as,
This will works only if you form page and submit code are in same page ( process.php )
<?php echo"<form method='post' action='process.php'>
<tr><td>Nama Jurusan</td>
<td>:</td>
<td><input type='text' name='jurusan' value='".$_POST['jurusan']."' size='50%'></td>
</tr>
<tr>
<td>Nama Laboratorium</td>
<td>:</td>
<td><input type='text' name='lab' value='".$_POST['lab']."' size='50%'></td>
</tr>
<input name='submit' type='submit' id='ajukan' value='Ajukan'>
</form>";?>
Also you have error in your code in line
<td><input type='text' name='lab' size='50%></td>
it should be <td><input type='text' name='lab' size='50%'></td>

Answer 2

If your form is still available in the process.php file, change it like this:
echo "<form method='post' action='process.php'>
<tr><td>Nama Jurusan</td>
<td>:</td>
<td><input type='text' name='jurusan' size='50%'";
if (isset($_POST['jurusan']))
{
echo " value=\'$_POST['jurusan']\'";
}
echo "></td>
</tr>
<tr>
<td>Nama Laboratorium</td>
<td>:</td>
<td><input type='text' name='lab' size='50%'";
if (isset($_POST['lab']))
{
echo " value=\'$_POST['lab']\'";
}
echo "></td>
</tr>
<input name='submit' type='submit' id='ajukan' value='Ajukan'>
</form>";

Answer 3

you need to use PHP sessions.
add the following string to your process.php page
session_start();
$_SESSION['prev_values'] = $_POST;
and the following to your form page
$lab = "";
$jur = "";
session_start();
if(isset($_SESSION['prev_values'])){
$jur = $_SESSION['prev_values']['jurusan'];
$lab = $_SESSION['prev_values']['lab'];
}
echo
"<form method='post' action='process.php'>
<tr>
<td>Nama Jurusan</td>
<td>:</td>
<td><input type='text' name='jurusan' size='50%' value='$jur'></td>
</tr>
<tr>
<td>Nama Laboratorium</td>
<td>:</td>
<td><input type='text' name='lab' size='50%' value='$lab'></td>
</tr>
<input name='submit' type='submit' id='ajukan' value='Ajukan'>
</form>";
SECURITY NOTICE:
Please note: this script is basic and it is vulnerable to XSS (just to name one). As a rule of thumb, you should NEVER display directly user inputs without some form of sanitation