Lowest unique bid coding problem

JayQ

Hello. I've made this code to calculate if there is a lower unique bid ($lower_bid_exist = TRUE) than the one entered ($auctionBID). However there is something wrong with the code: sometimes the script says that there are no lower unique bids ($lower_bid_exist = FALSE) when there in fact are!

$low_sql	= "SELECT bid FROM bids WHERE bid<'{$auctionBID}' AND auction='{$auctionID}'";

$low_query	= mysql_query($low_sql);


while($low_result = mysql_fetch_assoc($low_query)) {
	if($low_bids[$low_result["bid"]] >= 1) {
		$low_bids[$low_result["bid"]]++;
	} else {
		$low_bids[$low_result["bid"]] = 1;	
	}		
}

if(count($low_bids) == 0) {
	$lower_bid_exist = FALSE;
} else {
	while(list($temp_bid, $temp_count) = each($low_bids)) {
		if($temp_count == 1) {
			$lower_bid_exist = TRUE;
		} else {
			$lower_bid_exist = FALSE;
		}
	}
}

bogu

in this line:

if(count($low_bids) == 0)

u'll get a warning if the query dont return any results ...

So declare your array at the begining ...

$low_bids = array();

In rest your code seems OK, I cant see anything wrong, maybe u should debug it more carefully ...

And one more thing, ORDER your SELECT by bid field DESC, if your function is recursive u need to take the ids DESC not random ...

JayQ

Thank you, ordering the bid field by ASC seemed to solve the problem. I'll let you now if anything is wrong.

JayQ

I was wrong the error wasn't fixed by changing ORDER BY. Here are my actual values where the error occurs:

TABLE BIDS:
bid, auction
1 nok
1 nok
1 nok
1 nok
3 nok
4 nok
5 nok
6 nok
8 nok
8 nok
9 nok
16 nok
17 nok

When I enter $auctionbid = 9 , $auctionid = nok
The code returns $lower_bid_exist = FALSE;

laserlight

You might be able to do something like this:

$low_sql = "SELECT bid, COUNT(bid) as bid_count
	FROM bids
	WHERE bid<'{$auctionBID}' AND auction='{$auctionID}'
	GROUP BY bid";
$low_query = mysql_query($low_sql);

$low_bids = array();
if (mysql_num_rows($low_query) > 0) {
	$lower_bid_exist = true;
	while ($row = mysql_fetch_assoc($low_query)) {
		$low_bids[$row['bid']] = $row['bid_count'];
	}
} else {
	$lower_bid_exist = false;
}

JayQ

I'm sorry that didn't do it. I think the hard part about this is that "$lower_bid_exist = true" is only supposed to turn out when there is no single row with a lower bid, for example nok 9 is not the lowest unique bid because there are many lower "singles". If all the bid 1-8 at least had 2 rows each only then is $lower_bid_exist supposed to be true.

laserlight

Oh, sorry. You want to calculate if there is a lower unique bid.

A slight modification by checking that bid_count=1 should do the trick:

$low_sql = "SELECT bid, COUNT(bid) as bid_count
    FROM bids
    WHERE bid<'{$auctionBID}' AND bid_count=1 AND auction='{$auctionID}'
    GROUP BY bid";
$low_query = mysql_query($low_sql);

$low_bids = array();
if (mysql_num_rows($low_query) > 0) {
    $lower_bid_exist = true;
    while ($row = mysql_fetch_assoc($low_query)) {
        $low_bids[$row['bid']] = $row['bid_count'];
    }
} else {
    $lower_bid_exist = false;
}

This also shows $lower_bid_exist is a misleading variable that could be better renamed as $unique_lower_bid_exist

laserlight

hmm... on second thought, that may not work, and chances are you are on an old version of mysql that doesnt support subqueries.

Still, there isnt a problem:

$low_sql = "SELECT bid, COUNT(bid) as bid_count
    FROM bids
    WHERE bid<'{$auctionBID}' AND auction='{$auctionID}'
    GROUP BY bid";
$low_query = mysql_query($low_sql);

$low_bids = array();
$unique_lower_bid_exist = false;
if (mysql_num_rows($low_query) > 0) {
    while ($row = mysql_fetch_assoc($low_query)) {
		if ($row['bid_count'] == 1) {
			$low_bids[] = $row['bid'];
			$unique_lower_bid_exist = true;
		}
    }
}

Note that now $low_bids is a numerically indexed array that contains the unique bids that are lower than the one given. Also I have renamed the flag to $unique_lower_bid_exist

JayQ

That seems to do the trick, all my calculations now turn out to be correct. Thanks for the help!

euau

I've been looking for a "lowest unique bid" auction script and was wonder if any of you have such a script for sale or can any of you point me in the direct of one.

Thank in advance 🙂