mysql returns not exact value in max function when dealing with floats?

Question

Look at this query please

SELECT max( val_amd ) FROM `best_deposits` 

I have the max value in the table equal to 14.6(the fields has type float),

But it returns 14.3599996566772

why does it happen, and how can i get the exact value?

Thanks much

• Ned Batchelder: I hope you meant that you stored 14.36 in the field...
• oezi: please see my edit and the providet links

Answer 1

floats are evil!

NEVER use floats for storing amounts or prices. instead of that, use an int and store the amount in cents. thats the only way to get around those problems forever.

why this happens: because floats can't be saved exactly in many cases (such as 0.6 in your case)

PS: we had those questions a hundret times for different languages till now:

• Use Float or Decimal for Accounting Application Dollar Amount?
• PHP rounding problem (5.2.3)?
• Rounding problem with double type
• Javascript rounding v c# rounding
• Python rounding problem
• ... and a lot more

EDIT: to your comment: as i said:

use an int and store the amount in cents

(alternatively you could use an DECIMAL(10,2) (or how big/how much decimal places you need)... not sure about how this works)

• Simon: so, how can i store the float value in table? what type i must use? (it's boring to have two fields for each value:/)

Answer 2

Or you better use "decimal" with length 10,2 or something like that for storing prices.

• Marc B: double is still a floating point value. Doing a display length of 10,2 won't change the rounding issues with floats. At most it'll just hide them and lead to greater confusion while debugging.
• Yasen Zhelev: My mistake. I meant decimal(10,2) as @oezi wrote.