Precision is the total number of digits to the left and right of the decimal point. The scale option specifies the minimum number of digits after the decimal point when an arithmetic result is truncated to the maximum precision.

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 will be kept in the result. If scale is 4, the result will be a DECIMAL(15,4). If scale is 2, the result will be a DECIMAL(15,2). In both cases, there is a possibility of overflow.