Arithmetic Operators

You can use an arithmetic operator in an expression to negate, add, subtract, multiply, and divide numeric values. The result of the operation is also a numeric value. Some of these operators are also used in date arithmetic. Table 3-2 lists arithmetic operators.

Table 3-2 Arithmetic Operators

Operator	Purpose	Example
+ -	Denotes a positive or negative expression. These are unary operators.	SELECT * FROM orders WHERE qtysold = -1; SELECT * FROM emp WHERE -sal < 0;
* /	Multiplies, divides. These are binary operators.	UPDATE emp SET sal = sal * 1.1;
+ -	Adds, subtracts. These are binary operators.	SELECT sal + comm FROM emp WHERE SYSDATE - hiredate > 365;

Do not use two consecutive minus signs (--) in arithmetic expressions to indicate double negation or the subtraction of a negative value. The characters -- are used to begin comments within SQL statements. You should separate consecutive minus signs with a space or a parenthesis.

See Also: "Comments" for more information on comments within SQL statements.