|The list of following functions are mainly used to calculate group
of data or group of columns, and also known as "group-functions" or
"aggregated column functions"
|Aggregate functions in Oracle, are usually used with the GROUP
BY clause, to return a list which is grouped by one or more columns,
with a distinct result for each of the groupings. The HAVING clause, is
a companion clause to GROUP BY clause, which specifies certain group to
appear in the results.
SELECT JOB, AVG(SAL) "AVG",