Decimal Precision and Rounding in SQL Server

Jiri D. provides a warning:

Do you ever worry about how you declare NUMERIC or DECIMAL data types in SQL?
Do you sometimes “add a bit more” precision—just to be safe?
Have you considered how that small decision could actually change your arithmetic results?

I ran into this recently when comparing data between two environments that should have produced identical results. One calculated field was slightly off — and the culprit turned out to be a difference in numeric data type declarations.

Read on to see what happened. The differences weren’t massive, but if you were expecting an exact match, seeing a difference, even at the 7th or 8th spot after the decimal, could be jarring.