Column function expressions can be used in the SELECT clause to perform calculations. We have a table: EMPLOYEE_TBL
If we wanted to know the difference between the minimum and maximum RATE_HOUR, we could do the following:
SELECT (MAX(RATE_HOUR) – MIN(RATE_HOUR))
Calculations are evaluated in the following order:
1. Expressions within parentheses with the innermost first.
2. Multiplication and division.
3. Addition and subtraction.
4. Left to right.