Codeigniter: Get affected fields in update - php

Question

There's a way to get which fields were modified after a update query?
I want to keep track what field XXX user modified... any ways using active records?

Answer 1

I needed this exact functionality so I wrote this code. It returns the number of fields that were affected.
FUNCTION STARTS:
function mysql_affected_fields($sql)
{
// Parse SQL update statement
$piece1 = explode( "UPDATE ", $sql);
$piece2 = explode( "SET", $piece1[1]);
$sql_parts['table'] = trim($piece2[0]);
$piece1 = explode( "SET ", $sql);
$piece2 = explode( "WHERE", $piece1[1]);
$sql_parts['set'] = trim($piece2[0]);
$fields = explode (",",$sql_parts['set']);
foreach($fields as $field)
{
$field_parts = explode("=",$field);
$field_name = trim($field_parts[0]) ;
$field_value = trim($field_parts[1]) ;
$field_value =str_replace("'","",$field_value);
$sql_parts['field'][$field_name] = $field_value;
}
$piece1 = explode( "WHERE ", $sql);
$piece2 = explode( ";", $piece1[1]);
$sql_parts['where'] = trim($piece2[0]);
// Get original field values
$select = "SELECT * FROM ".$sql_parts['table']." WHERE ".$sql_parts['where'];
$result_latest = mysql_query($select) or trigger_error(mysql_error());
while($row = mysql_fetch_array($result_latest,MYSQL_ASSOC))
{
foreach($row as $k=>$v)
{
if ($sql_parts['field'][$k] == $v)
{
}
else
{
$different++;
}
}
}
return $different;
}

Answer 2

There is no way using active record to get this easily, but if you are only supporting one specific database type (let's say MySQL) you could always use Triggers?
Or, Adam is about right. If you have a WHERE criteria for your UPDATE you can SELECT it before you do the UPDATE then loop through the old and new versions comparing.
This is exactly the sort of work Triggers were created for, but of course that puts too much reliance on the DB which makes this less portable yada yada yada.

Answer 3

solution
instructions:
SELECT row, that user wants to modify
UPDATE it
Compute differences between selected and update it
Store the differences somewhere (or mail it, show it, whatever)
simple