Oracle report with aggregate function, subquery and group by

We are writing queries to get information that clients wish to display. There are 30 tables Oracle 10 g and using Oracle report. We only knew to use Union for condition in query. Our challenges is aggregate function, subquery and group by, too. How can we solve the challenges?

>>>>>>>>>>>> CREDITS BREAK DOWN <<<<<<<<<<<<<
SELECT statement
UNION
SE开发者_JAVA技巧LECT   statement

According to requirement, above query is OK. Is it possible to rewrite better way?

What kind of question is this?

How do you want us to answer such a question?

How about learning what aggregates are, learning what a group by does and finding out how to correctly group by a column. You need to specify and provide sample data to us, with expected results.

Here is a direct link to display some aggregates with example: http://psoug.org/reference/group_by.html

Only then can we help assist in writing a query / report for you. Did you really always use UNION in your queries and you didn't know what joins or subqueries are? You really need a SQL Developer or a dba.