Question

I have a 1-cent-auction website that increases bids by 1 cent on every bid

The current_bid field is a DOUBLE on mysql that represents the bid in dollars, and i need to avoid cases like 0.2 + 0.1 = 0.299999999
(not sure if it’s the right result format but you get the idea)

I have had lots of cases other than with these two numbers because of precision..

Now, here is my code : (i am hoping its correct and efficient, otherwise, i am open to your ideas)

UPDATE `auctions` SET 
`current_bid` = ROUND(ROUND(`current_bid` * 100) + 1)/100
...

Answer 1

Is it too late to switch to DECIMAL? Floating point column types provide approximate values; it’s a well known fact and it’s by design.