保持变量的过去值

Question

I put a variable (price) to a html form from database. then user changes the price and submit the form and variable is updated in database. I want to keep previous value (last state and show it in the form) but if I update the form variable keeps updating.

What is best way to remember previous value of variable (in array for example) ?

Answer 1

If you're updating this data in an actual Database, you should create a parallel table that holds the value of the previous row.

Otherwise, if you're updating only an array, you can just create a copy prior to updating the array: http://codepad.org/SvlasJ7f

<?php

    $array = array('Old Value');
    $lastarray = '';

    updateArray($array,'New Value');

    function updateArray(&$a,$v) {
        $GLOBALS[lastarray] = $a;
        $a = array($v);
    }
?>