MySQL - Select differently - php

Question

I have this query, which selects a distinct value for a column, but I need something else in that query too. I need it to fetch a different row associated with the main select.
Let me illustrate...
This is my query:
$sql = 'SELECT DISTINCT user_id FROM ' . DONATION_SECURITY_TABLE;
$result = mysql_query($sql);
$rows = mysql_fetch_assoc($result);
mysql_free_result($result);
return $rows;
As you see it returns this query returns the DISTINCT of user_id.
If I use a function like this in a double foreach loop created using the return of the query above:
public function get_donor_status($user_id)
{
global $db;
$sql = 'SELECT payment_status FROM ' .DONATION_SECURITY_TABLE .
" WHERE user_id = '" . (int) $user_id . "'";
$result = $db->sql_query($sql);
$row = $db->sql_fetchrow($result);
$payment_status = $row['payment_status'];
$db->sql_freeresult($result);
return $payment_status;
}
This function would return Completed for user_id 2, but I want it to say Pending instead. How would I change my query so it returns the last value for the corresponding user_id?
If I'm not clear enough, please let me know so I can reexplain.

Answer 1

Just select the last row for the user:
"SELECT payment_status FROM " . DONATION_SECURITY_TABLE . " WHERE user_id = '" . (int) $user_id . "' ORDER BY donation_id DESC LIMIT 1"

Answer 2

How about this?
$sql = 'SELECT payment_status FROM ' .DONATION_SECURITY_TABLE .
" WHERE user_id = '" . (int) $user_id . "' ORDER BY donation_id DESC LIMIT 1";

Answer 3

You can actually get everything in one SQL statement, no need for a double loop:
SELECT
user_id, payment_status
FROM
DONATION_SECURITY_TABLE t1
WHERE
donation_id = (select max(donation_id) from DONATION_SECURITY_TABLE t2 WHERE t2.user_id = t1.user_id)
ORDER BY
user_id