I was amazed at how handy the Pivot function can be. It empowers the user to provide aggregate and denormalized view of a data set which could be a query or a table. In this article I am going to provide a brief example of the pivot function.

First of all let us set some data: 

CREATE TABLE SAMPLE_TRANSACTIONS
(
TRANSACTION_ID NUMBER(8),
COMPANY_NAME VARCHAR2(30),
STATE VARCHAR2(2),
TRANSACTION_AMOUNT NUMBER(10,2)
);
INSERT INTO SAMPLE_TRANSACTIONS VALUES
( 1 , 'PALERMO' , 'TX' , 300.22
);
INSERT INTO SAMPLE_TRANSACTIONS VALUES
( 2 , 'PALERMO' , 'CT' , 600.22
);
INSERT INTO SAMPLE_TRANSACTIONS VALUES
( 3 , 'PALERMO' , 'PA' , 900.669
);
INSERT INTO SAMPLE_TRANSACTIONS VALUES
( 4 , 'BOLOGNA' , 'TX' , 500.22
);
INSERT INTO SAMPLE_TRANSACTIONS VALUES
( 5 , 'BOLOGNA' , 'CT' , 1100.22
);
INSERT INTO SAMPLE_TRANSACTIONS VALUES
( 6 , 'BOLOGNA' , 'PA' , 100.669
);
INSERT INTO SAMPLE_TRANSACTIONS VALUES
( 7 , 'PARMA' , 'NY' , 1300.22
);
INSERT INTO SAMPLE_TRANSACTIONS VALUES
( 8 , 'PARMA' , 'NJ' , 1600.22
);
INSERT INTO SAMPLE_TRANSACTIONS VALUES
( 9 , 'PARMA' , 'CA' , 1900.669
);

Now let us view the data:

SELECT * FROM SAMPLE_TRANSACTIONS;

Now let us create a report that provides the sum of the transactions by company at a state level:
Let us first execute this query:

SELECT *
FROM
( SELECT COMPANY_NAME , STATE , TRANSACTION_AMOUNT
FROM SAMPLE_TRANSACTIONS
) PIVOT
( SUM(TRANSACTION_AMOUNT)
FOR
COMPANY_NAME IN
('BOLOGNA' AS BOLOGNA , 'PARMA' AS PARMA, 'PALERMO' AS PALERMO) )
ORDER BY STATE;

Results:

Now let us create a report that provides the sum of the transactions by state at a company level:

Let us first execute this query:

SELECT *
FROM
( SELECT COMPANY_NAME , STATE , TRANSACTION_AMOUNT FROM SAMPLE_TRANSACTIONS
) PIVOT
( SUM(TRANSACTION_AMOUNT)
FOR STATE IN ('CT' CT , 'NY' NY, 'TX' TX) )
ORDER BY COMPANY_NAME;

Results

As you can see above there are a lot of possibilities on how to leverage the pivot function. For further reading I recommend this link Oracle Pivot.