Question about retrieving data from two tables

Question

Hi everyone.
I've been working on this and was wondering what the correct way of handling this would be.
I have two tables, a Billing Table that contains invoices and related information, and a Payments Table that contains payments and related information to that.
Both tables contain a Date Column for the date that the Invoice was generated or the Payment was made.
I want to get a list of all Invoices and the respective payments if the invoice was generated between two dates OR the payment was made between these two dates.
I can get a list of the invoices and their payments if the invoice was generated between those dates.  I can get a list of the payments if they were made between those dates.  But I can't seem to figure out how to do both.
How do I Join two tables and have it return the data from both tables if either meets the required Date Period?
Here is the SQL that I have so far.  This SQL returns all of the Invoices and Payments IF the Invoice was generated between these two dates (Or updated). 
SELECT Billing.ID AS [BID], Billing.AttachmentName, Billing.BillingType, Billing.Invoice, Billing.Description, Billing.Amount, Billing.DateCreated AS [BillingDate],
Payments.ID AS [PID], Payments.Type AS PaymentType, Payments.Payment, Payments.PaymentNote, Payments.Reason AS [BillReason], Payments.DateCreated AS [PaymentDate],
Customers.ID AS [CID], COALESCE(NULLIF(Customers.Company,'') + ' - ','') + Customers.LName + ', ' + Customers.FName AS [Name],
Jobs.ID AS [JID], Jobs.JobType, Jobs.JobStatus, Jobs.JobStatusDate
FROM Billing LEFT OUTER JOIN Payments ON Payments.BillingID = Billing.ID
RIGHT OUTER JOIN Customers ON Customers.ID = Billing.CustomerID
RIGHT OUTER JOIN Jobs ON Jobs.ID = Billing.JobID
WHERE
Billing.BillingType = 'Invoice' AND Billing.PaidInFull = 'No' AND Billing.Collections = 'No' AND Billing.ChargeOff = 'No' AND Billing.Lien = 'No' AND Billing.InvoiceCanceled = 'No'
AND (Billing.DateCreated >= '1/1/2014' AND Billing.DateCreated <= '8/13/14') OR (Billing.DateUpdated >= '1/1/14' AND Billing.DateUpdated <= '8/13/14')
ORDER BY Name Asc, Billing.Invoice, PID
Thanks for your help, I really appreciate it.
-Matt-

Answer 1

I don't quite follow your query, but your description leads me to think that you need the set of Billing IDs for bills that were created as defined or that have payments that were created as defined.  From that set of IDs you then simply want all Bills
and their associated payments.  So how do you get that set of IDS?  One way is the union operator: 
with allbill (billID) as (
select ID from dbo.Billings where DateCreated between ...
union 
select BillingID from dbo.Payments where DateCreated between ... )
select ...
from allbill inner join dbo.Billings as bill on allbill.billID = bill.ID inner join dbo.Payments as pay 
on bill.ID = pay.BillingID 
order by ... ;
Your description leads me to believe that you query is much more complicated, but the basic idea is the union in the CTE - generate one combined set of bill IDs that identify all your bills of interest.  Note that I assumed that a payment cannot exist
with an associated billing.