Question

I want to do something like this:

    SELECT * FROM `sometable` 
    WHERE `smth`=`smth` 
    ORDER BY (`r1`-`r2`)

but when r2>r1, difference is not negative, and it has a very big value… How to get negative value after subtraction?

Answer 1

well, I supose that you have unsigned values in r1 and r2… to get negative values try running this:

SET sql_mode='NO_UNSIGNED_SUBTRACTION';