SQL四舍五入问题

Question

Consider these values which are of type MONEY (sample values and these can change)

select 4796.529 + 1585.0414 + 350.9863 + 223.3549 + 127.6314+479.6529 + 158.5041

for some reason I need to round each value to a scale of 3 like this

select round(4796.529,3)+ round(1585.0414,3)+ round(350.9863,3)+ round(223.3549,3)+ round(127.6314,3)+ round(479.6529,3)+ round(158.5041,3)

but when I take the sum they shows a very minor variation. first line of code returns 7721.7000 . and the second one 7721.6990 . But this variation in not acceptable. What is the best way to solve this ?

Answer 1

As Whencesoever said, your problem is mathmatical one, not a programming error.

• 12.5 + 11.6 = 24.1
• ROUND(12.5) + ROUND(11.6) = 25
• ROUND(12.5 + 11.6) = 24

I'd talk with the business and figure out where they want the rounding applied.

Also, as a side note, MONEY is a terrible datatype. If you can, you may want to consider switching to a DECIMAL . See Should you choose the MONEY or DECIMAL(x,y) datatypes in SQL Server?

Answer 2

When you round numbers before you sum them you will get a different result than if you round numbers after you have summed them. Simple as that. There is no way to solve this.