Unknown Column 'member_id' in 'where clause' - php

Question

I've searched this website for a solution but no result.
I'm stuck on the following problem, my code gives the Unknown Colum 'member_id' in 'where clause' error. Never heard of it before.. so I am a bit confused right now.
This is my code :
<?php
require("db.php");
$id = $_REQUEST['member_id'];
$result = mysql_query("SELECT * FROM members WHERE member_id = '$id'");
$test = mysql_fetch_array($result);
if (!$result)
{
die("Error: Data not found..");
}
$admin=$test['admin'] ;
$firstname=$test['firstname'] ;
$lastname=$test['lastname'] ;
$mail= $test['mail'] ;
$login=$test['login'] ;
$passwd=$test['passwd'] ;
if(isset($_POST['save']))
{
$admin_save = $_POST['admin'];
$firstname_save = $_POST['firstname'];
$lastname_save = $_POST['lastname'];
$mail_save = $_POST['mail'];
$login_save = $_POST['login'];
$passwd_save = md5($_POST['password']);
mysql_query("UPDATE lijst SET admin ='$admin_save',firstname ='$firstname_save',lastname ='$lastname_save', mail ='$mail_save', login ='$login_save',
passwd ='$passwd_save' WHERE member_id = '$id'")
or die(mysql_error());
echo "Saved!";
header("Location: main.php");
}
mysql_close($conn);
?>
The form :
<form method="post">
<table>
<tr>
<td>Admin</td>
<td><input type="text" name="admin" class="text w_20" value="<?php echo $admin ?>"/></td>
</tr>
<tr>
<td>Voornaam</td>
<td><input type="text" name="firstname" class="text w_20" value="<?php echo $firstname ?>"/></td>
</tr>
<tr>
<td>Achternaam</td>
<td><input type="text" name="lastname" class="text w_20" value="<?php echo $lastname ?>"/></td>
</tr>
<tr>
<td>E-mail</td>
<td><input type="text" name="mail" class="text w_20" value="<?php echo $mail ?>"/></td>
</tr>
<tr>
<td>Gebruikersnaam</td>
<td><input type="text" name="login" class="text w_20" value="<?php echo $login ?>"/></td>
</tr>
<tr>
<td>Password</td>
<td><input type="text" name="passwd" class="text w_20" value="<?php echo $passwd ?>"/></td>
</tr>
<tr>
<td> </td>
<td><input type="submit" name="save" value="update" /></td>
</tr>
</table>
</form>

Answer 1

The error is saying there is no field member_id in the database table lijst. Add the field or remove the condition from the WHERE clause.
Given the SQL you just posted, your table is called members not lijst. So change the query:
UPDATE members ......
Edit: your MD5 problem is because your html input is named passwd but you are targeting password in the POST array:
$passwd_save = md5($_POST['password']);
Change to:
$passwd_save = md5($_POST['passwd']);
Finally, your query is vulnerable to SQL Injection. As a quick fix, run your user input through mysql_real_escape_string(). Or even better, switch to a modern MySQL API such as PDO, and use parameterised queries.