The position of the decimal point is determined by the precision and the scale of the number: precision is the total number of digits to the left and right of the decimal point; scale is the minimum number of digits after the decimal point when an arithmetic result is truncated to the maximum precision.
Choosing an appropriate decimal point position is typically determined by:
The type of arithmetic procedures you perform Multiplication, division, addition, subtraction, and aggregate functions can all have results that exceed the maximum precision.For example, when a DECIMAL(8,2) is multiplied with a DECIMAL(9,2), the result could require a DECIMAL(17,4). If precision is 15, only 15 digits are kept in the result. If scale is 4, the result is a DECIMAL(15,4). If scale is 2, the result is a DECIMAL(15,2). In both cases, there is a possibility of overflow error.
The relationship between scale and precision values The scale sets the number of digits in the fractional part of the number, and cannot be negative or greater than the precision.