Each column in the query output has a default name. If you don't like the default name, you can specify a new name for any column in the query output by using the AS clause. The following statement shows you a good example:

SQL> SELECT department_id AS ID, MIN(salary) AS Low,

2 MAX(salary) AS High, AVG(salary) AS Average

3 FROM employees GROUP BY department_id

4 HAVING AVG(salary) < 5000;

  ID  LOW  HIGH AVERAGE

---------- ---------- ---------- ----------

  30  2500 11000  4150

  50  2100  8200 3475.55556

  10  4400  4400  4400