There are four basic arithmetic functions; plus(+), minus(-), divide(/) and multiply(*). Their use is straightforward. If you want to perform a calculation the format is as follows:

A few illustrations:

SQL> SELECT NAME, SALARY, COMM, SALARY + COMM ç plus operator

The results table will look like this:

It is important to note that in the results table a column titled SALARY + COMM will be returned as specified in the SELECT clause. This column is not physically stored in the database but rather it is calculated as a result of the query.

Note that some of the 'SALARY+COMM' columns are empty. Why? If every employee in the table has a value for salary why didn't it carry over to the 'SALARY+COMM' column? Because the 'COMM' column is defined as null which does not mean zero. The total could not be calculated unless a numeric value had existed within the COMM column. Look at Watson, his commission was equal to zero so zero plus his salary was put into the SALARY+COMM column.

If for example the value carried in the salary column is a monthly figure and you wanted an annual figure the following query would accomplish that by using the multiply operator:

SQL> SELECT NAME, SALARY * 12 ç multiply operator on a column

The results table should look like this:

For you to try:

1. Consider that the value in the Salary column is a monthly figure. Suppose that you are the owner of this company and you want to find out how much each employee would be paid per month if you increased his or her salary by 5%. Write a SQL query to get this information.
2. Again, consider that the value in the Salary column is a monthly figure. Suppose that you as the owner of this company want to compute how much each employee would be paid per month if you gave everyone a 3% pay cut. Write a SQL query to get this information.

Go here to check your answers.

Last revised 10/21/1997 by J. Warren, Kennesaw State University

Department of Computer Science and Information Systems