Help to aggregate 3 tables into 1

Question

Hello every one,
I have one master table with 2 details and like to aggregate them with a view using SUM.
Master table = purchase : purchase_id, customer_id, purchase_date, store_id, ...
First detail = purchased_products: product_id, purchase_id, qauntity, price, ...
Second detail = paid_taxes: tax_id, purchase_id, amount, ...
Now I want to have a view that aggregates the products and taxes for all the customers. The following view would show wrong sums because of the join:
CREATE OR REPLACE FORCE VIEW GGREGATED_PURCHASES_VIEW (customer_id, product_id, quantity, price, tax_id, amount) AS
SELECT pu.customer_id,
pr.product_id,
SUM(pr.quantity) as quantity,
SUM(pr.price) as price,
tx.tax_id,
SUM(tx.amount) as amount
FROM purchase pu
JOIN purchased_products pr ON pu.purchase_id=pr.purchase_id
LEFT OUTER JOIN paid_taxes tx ON pu.purchase_id=tx.purchase_id
GROUP BY pu.customer_id, pr.product_id, tx.tax_id
How can I do it correctly?

Answer 1

Hi,
Welcome to the forum!
You probably want to do one (possibly both) of the one-to-many joins in a separate query, and then join the aggregated results.
Sorry, I don't understand exactly what you want.
Do you want one row of output for every customer_id? This would make sense, and it would be easiest.
Do you want one row of output for every combination of customer_id and purchase_id? If so, what does the tax amount column represent?
Do you want one row of output for every combination of customer_id and tax_id? If so, what do the quantity and price columns represent?
Do you want one row of output for every combination of customer_id, purchase_id and tax_id? If so, what do any of the SUMs represent?
Whenever you have a question, it helps to post:
(1) The version of Oracle (and any other relevant software) you're using
(2) A little sample data (just enough to show what the problem is) from all the relevant tables
(3) The results you want from that data
(4) Your best attempt so far (formatted) (You posted the code, but its unformatted and hard to read.)
Executable SQL statements (like "CREATE TABLE AS ..." or "INSERT ..." statements) are best for (2).
Formatted tabular output is okay for (3). Type these 6 characters:
(small letters only, inside curly brackets) before and after sections of formatted text, to preserve spacing.
Edited by: Frank Kulash on Sep 24, 2009 2:11 PM