PHP querying mysql db for data limited to the last month

So I have this code I'm working with (pasted below) that queries a mysql db table called timetracking. The goal of the page is to search the db for all data based on a certain engineer, sorted by product and it takes pre-defined values based on actions performed, sums them based on product and display's the percentage of time an engineer has spent on each product. Everything works great except I need to limit the results to the last months data only, but everything I try seems to just break it. Can anyone push me in the right direction a little? I have tried using BETWEEN in the SELECT statement, some while statements and if statements, and all I do is keep breaking it. If anyone has any ideas, it would be exceptionally helpful. Thanks in advance, Vinny <?php $total = 0; $today = date('Y-m-d h:i:s'); $monthago = date("Y-m-d h:i:s", mktime(date("h"), date("i"), date("s"), date("m")-1, date("d"), date("Y"))); echo "Today = ", $today; echo "<br>One Month Ago = ", $monthago, "<br>"; $query = "SELECT *, SUM(timespent) FROM timetracking WHERE engineer = '$engineer' GROUP BY product"; $result = mysql_query($query) or die(mysql_error()); $result2 = mysql_query($query) or die(mysql_error()); echo "<center>"; while($row = mysql_fetch_array($result)){ $total = $row['SUM(timespent)'] + $total; } while($row = mysql_fetch_array($result2)){ $perc = $row['SUM(timespent)'] * 100 / $total; echo "[ <font color=#1E429B size=+1>", $row[product]. " = ". number_format($perc,2), "%</font> ]"; } ?>