Addition and Subtraction

Go Up to Exact Numerics (Language Reference Guide)

If both operands are exact numeric, adding or subtracting the operands produces an exact numeric with a precision of 18 and a scale equal to the larger of the two. For example:

CREATE TABLE t1 (n1 NUMERIC(16,2), n2 NUMERIC(16,3));
INSERT INTO t1 VALUES (12.12, 123.123);
COMMIT;

The following query returns the integer 135.243. The largest scale of the two operands is 3; therefore, the scale of the sum is 3.

SELECT n1 + n2 FROM t1;

Similarly, the following query returns the integer -111.003:

SELECT n1 - n2 FROM t1;

If either of the operands is approximate numeric (FLOAT, REAL, or DOUBLE PRECISION), the result is DOUBLE PRECISION.