Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
Why when I save a value of say 40.54 in SQL Server to a column of type Real does it return to me a value that is more like 40.53999878999 instead of 40.54? I’ve seen this a few times but have never figured out quite why it happens. Has anyone else experienced this issue and if so causes it?
Have a look at What Every Computer Scientist Should Know About Floating Point Arithmetic.
Floating point numbers in computers don’t represent decimal fractions exactly. Instead, they represent binary fractions. Most fractional numbers don’t have an exact representation as a binary fraction, so there is some rounding going on. When such a rounded binary fraction is translated back to a decimal fraction, you get the effect you describe.
For storing money values, SQL databases normally provide a DECIMAL type that stores exact decimal digits. This format is slightly less efficient for computers to deal with, but it is quite useful when you want to avoid decimal rounding errors.