A packed ``exact'' fixed-point number. M is the total number of digits and D is the number of decimals. The decimal point and (for negative numbers) the '-' sign are not counted in M. If D is 0, values have no decimal point or fractional part. The maximum number of digits (M) for DECIMAL is 64. The maximum number of supported decimals (D) is 30. If UNSIGNED is specified, negative values are disallowed.
If D is omitted, the default is 0. If M is omitted, the default is 10.
All basic calculations (+, -, *, /) with DECIMAL columns are done with a precision of 64 decimal digits.