how to handle a large php mysql $_POST UPDATE/INSERT - php

Question

I'm trying to do something like this so I don't have to type out all of my post entries. I can't seems to get this to work though.
edit: added some changes.
foreach($_POST as $key => $value)
{
$key = "'".mysql_real_escape_string($key)."'";
$value = "'".mysql_real_escape_string($value)."'";
$qstring = "UPDATE load_test SET ".$key."=".$value." WHERE Id = '".$_POST['id']."'";
mysql_query($qstring);
}

Answer 1

What you are trying to do here is incredibly, dangerously insecure.
// List the fields that may be updated here
$expectedFields = array('fielda', 'fieldb');
// Updated values to be stored here
$updates = array();
// Generate the update strings
foreach ($_POST as $key => $value) {
if (in_array($key, $expectedFields)) {
$updates[] = "`$key` = '".mysql_real_escape_string($key)."'";
}
}
// Do all updates at once
$qstring = "UPDATE load_test SET " . join(', ', $updates) . " WHERE Id = '" . mysql_real_escape_string($_POST['id']) . "'";
mysql_query($qstring);
This improves several things
All updates happen in one query, rather than one per field
The fields are validated (and sanitised, as they're only accepted if they're in the valid list)
The ID value is also sanitised

Answer 2

foreach($_POST as $k=>$v){
#$select.=" `".mysql_real_escape_string($k)."` = '".mysql_real_escape_string($v)."',";
}
$select = rtrim($select,',');
$select = "UPDATE load_test SET".$select." WHERE id=".$_POST['id'];
mysql_query($select) or die(mysql_error());;
try this is alot faster then the previous one you want need to do more then 1 query
and other then that i think it's safe enough to escape the key since trying updating a column that doesn't exist doesn't get you anywhere, and trying to make an injection escaping will protect you from that, you should though make sure the id is numeric