I couldn’t find anything that rejects or confirms whether SQL Server ‘MONEY’ data type is a decimal floating point or binary floating point.
In the description it says that MONEY type range is from -2^63 to 2^63 – 1 so this kind of implies that it should be a binary floating point.
But on this page it lists MONEY as “exact” numeric. Which kind of suggests that MONEY might be a decimal floating point (otherwise how is it exact? or what is the definition of exact?)
Then if MONEY is a decimal floating point, then what is the difference between MONEY and DECIMAL(19,4) ?
Neither. If it were an implementation of floating point it would be subject to the same inaccuracies as FLOAT and REAL types. See Floating Point on wikipedia.
MONEY is a fixed point type.
It’s one byte smaller than a DECIMAL(19,4), because it has a smaller range (922,337,203,685,477.5808 to 922,337,203,685,477.5807) as opposed to (-10^15+1 to 10^15-1).