I have three tables: customers, salesorders and invoices. Customers have
salesorders and salesorders have invoices ( child tables have foreign
key columns to their parent).
I want to get a list of all invoices with their customers. This what I
came up with:
select
invoices.objectid,
invoices.invoicenumber,
invoices.invoicedate,
(select customer from salesorders where objectid = invoices.salesorderobjectid),
(select customernumber from customers where objectid = (select customer from salesorders where objectid = invoices.salesorderobjectid)),
(select lastname from customers where objectid = (select customer from salesorders where objectid = invoices.salesorderobjectid))
from invoices
Can I do this smarter as the three subselects select the same customer three times and I would think that 1 time is enough?
invoices.objectid,
invoices.invoicenumber,
invoices.invoicedate,
salesorders.customer,
customers.customernumber,
customers.lastname
FROM invoices
INNER JOIN salesorders ON (
salesorders.objectid = invoices.salesorderobjectid
)
INNER JOIN customers ON (
customers.objectid = salesorder.customer
)
You should do INNER and OUTER joins for connecting the tables by their foreign keys.
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Aaron Bono
Aranya Software Technologies, Inc.
http://www.aranya.com
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