Question

I have a blog. I wrote simple voting system. I might be wrong about the idea. i have a table like this

id title article TotalVotes VoteSum

when someone upvote article TotelVotes gets one point if someone downvote the article the VoteSum cloumn gets 1 point

when I display the article’s vote i do this

<?php
$Vote = $ROW['TotelVotes']-$ROW['VoteSum'];
?>

it works just fine but on my front page I want to show top articles so I made this mysql query

SELECT TotalVotes-VoteSum AS diff FROM `articles` ORDER BY `diff`  DESC

when i do this I recieve numbers like this 18446744073709551615 this happens for example when TotalVotes less than VoteSum

DATA TYPE IS INT UNSIGNED

what do I do wrong? Could you please help me? thanks.

Answer 1

you can use IF

SELECT IF(TotalVotes >= VoteSum, TotalVotes-VoteSum, VoteSum-TotalVotes) AS diff 
FROM `articles` 
ORDER BY `diff`  DESC

UPDATE

if you want to get negative values, make those columns as INT SIGNED so you can get negatives. And directly run your own query,

SELECT TotalVotes-VoteSum AS diff 
FROM `articles` 
ORDER BY `diff`  DESC

• SQLFiddle Demo (SIGNED INTEGER)