Three Queries Of One Table As One Stored Procedure?

Hi,
I currently have three queries running seperately which I'd like to join up..

However I'm sure it can be done..

Here goes:

I have one table which lists payments made (it stores a PaymentID from another table, a payment amount and an invoiceID)

Therefore there can be several records with the same PaymentID referenceing different invoices (i.e a user paying off several invoices with one payment)

I have one query which lists all of the invoices paid against one payment.

SELECT PaymentID, InvoiceID, PaymentAmount WHERE PaymentID = xxx AND PayType <> 'Credit'

I then have a second query which is ran against each individual invoice which shows the other payments which have been made against this invoice already


SELECT PaymentID, InvoiceID, PaymentAmount WHERE PaymentID <> xxx AND PayType <> 'Credit' AND InvoiceID = XXX


and final I have one query which lists the credits
SELECT PaymentID, InvoiceID, PaymentAmount WHERE PayType = 'Credit' AND InvoiceID = XXX


All of the above lets me see an payment, which invoices have been paid against that payment.. and then for each invoice, any other payment which were made beforehand, and finally any credits against that invoice.


I run these from an ASP page in a loop which is pretty inefficient way of doing it.

I would much prefer to amalgamate the three queries above so I could see what I was paying now, what had already been paid and what was credited against each invoice from a PaymentID.. all in query.

Is that possible?

Thanks
mtm81