Postmeta meta_value SUM

I think you need to provide more detail before anyone can help. For example, you want two values from the meta_key ‘start’. Are there multiple ‘start’ fields assigned to each post? If not, how do you select the two ‘start’ rows?

If you would make up a simple table of postmeta values as an example, it would help a great deal.

Only one start for each post and only one profit for each post and they share the same post_id. I will enter the between starts manually into query.

Please try this:

$begin_dt = '20130601';
$end_dt = '20130718';
$sql = "
SELECT SUM(pm1.meta_value) as total_profit
FROM $wpdb->postmeta pm1
JOIN $wpdb->postmeta pm2 ON pm2.post_id = pm1.post_id
WHERE pm1.meta_key = 'profit'
AND pm2.meta_key = 'start'
AND pm2.meta_value BETWEEN '$begin_dt' AND '$end_dt'
";
$total_profit = $wpdb->get_var($sql);
$total_profit += 0; // Make sure value is numeric
echo "<p>Total Profit = $total_profit</p>";

It works perfectly!
Thank you very much.
I will have to study this little piece of code in detail to learn something.
Thanx again!