php mysql simple update: cannot read values - php

Question

probably stupid question but...
I have a sample for PHP and MySQL, which doesn't work...
there are 3 php files:
list_records.php
update.php
update_ac.php
the problem is that 3rd one doesn't read variables from the 2nd. What am I doing wrong?
Here are my files/code:
list_records.php
<?php
$host="localhost"; // Host name
$username="root"; // Mysql username
$password=""; // Mysql password
$db_name="test"; // Database name
$tbl_name="test_mysql"; // Table name
// Connect to server and select database.
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");
$sql="SELECT * FROM $tbl_name";
$result=mysql_query($sql);
?>
<table width="400" border="0" cellspacing="1" cellpadding="0">
<tr>
<td>
<table width="400" border="1" cellspacing="0" cellpadding="3">
<tr>
<td colspan="4"><strong>List data from mysql </strong> </td>
</tr>
<tr>
<td align="center"><strong>Name</strong></td>
<td align="center"><strong>Lastname</strong></td>
<td align="center"><strong>Email</strong></td>
<td align="center"><strong>Update</strong></td>
</tr>
<?php
while($rows=mysql_fetch_array($result)){
?>
<tr>
<td><?php echo $rows['name']; ?></td>
<td><?php echo $rows['lastname']; ?></td>
<td><?php echo $rows['email']; ?></td>
<td align="center">update</td>
</tr>
<?php
}
?>
</table>
</td>
</tr>
</table>
<?php
mysql_close();
?>
update.php
<?php
$host="localhost"; // Host name
$username="root"; // Mysql username
$password=""; // Mysql password
$db_name="test"; // Database name
$tbl_name="test_mysql"; // Table name
// Connect to server and select database.
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");
// get value of id that sent from address bar
$id=$_GET['id'];
// Retrieve data from database
$sql="SELECT * FROM $tbl_name WHERE id='$id'";
$result=mysql_query($sql);
$rows=mysql_fetch_array($result);
?>
<table width="400" border="0" cellspacing="1" cellpadding="0">
<tr>
<form name="form1" method="post" action="update_ac.php">
<td>
<table width="100%" border="0" cellspacing="1" cellpadding="0">
<tr>
<td> </td>
<td colspan="3"><strong>Update data in mysql</strong> </td>
</tr>
<tr>
<td align="center"> </td>
<td align="center"> </td>
<td align="center"> </td>
<td align="center"> </td>
</tr>
<tr>
<td align="center"> </td>
<td align="center"><strong>Name</strong></td>
<td align="center"><strong>Lastname</strong></td>
<td align="center"><strong>Email</strong></td>
</tr>
<tr>
<td> </td>
<td align="center">
<input name="name" type="text" id="name" value="<?php echo $rows['name']; ?>">
</td>
<td align="center">
<input name="lastname" type="text" id="lastname" value="<?php echo $rows['lastname']; ?>" size="15">
</td>
<td>
<input name="email" type="text" id="email" value="<?php echo $rows['email']; ?>" size="15">
</td>
</tr>
<tr>
<td> </td>
<td>
<input name="id" type="hidden" id="id" value="<?php echo $rows['id']; ?>">
</td>
<td align="center">
<input type="submit" name="Submit" value="Submit">
</td>
<td> </td>
</tr>
</table>
</td>
</form>
</tr>
</table>
<?php
// close connection
mysql_close();
?>
update_ac.php
<?php
$host="localhost"; // Host name
$username="root"; // Mysql username
$password=""; // Mysql password
$db_name="test"; // Database name
$tbl_name="test_mysql"; // Table name
// Connect to server and select database.
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");
// update data in mysql database
$sql="UPDATE $tbl_name SET name='TEST', lastname='$lastname', email='$email' WHERE id='$id'";
$result=mysql_query($sql);
// if successfully updated.
if($result){
echo "Successful";
echo "<BR>";
echo "<a href='list_records.php'>View result</a>";
}
else {
echo "ERROR";
}
?>

Answer 1

u need to get the value in the server side from client side before inserting or updating them into the database.for this we have superglobal variables in php like $_GET,$_POST,$_REQUEST etc.
so include thses in your update_ac.php:
$lastname=$_POST[lastname];
$email=$_POST[email];
$id=$_POST[id];`
you can use $_REQUEST method if you are not sure by which method u passed the values from the form.but try to avoid it as it is less secure.

Answer 2

You need to get them from POST in the update_ac.php file like
$sql="UPDATE $tbl_name
SET name='TEST',
lastname='".$_POST['lastname']."',
email='".$_POST['email']."'
WHERE id=".$_POST['id'];

Answer 3

This is what you need in your update query
......lastname='".$_POST['lastname']."', email='".$_POST['email']."' WHERE id=".$_POST['id']
Whenever a form posts/submits a value to a file mentioned in an action, the file must access the values of form's field's name in $_POST array as $_POST['lastname'], $_POST['email']. etc. (if the method used is POST in form tag)
There are three ways of access submitted values:
GET http://php.net/manual/en/reserved.variables.get.php
POST http://php.net/manual/en/reserved.variables.post.php
REQUEST http://php.net/manual/en/reserved.variables.request.php