I am trying to write a SQL Statement that has three tables. I am looking at WIRE STANDS being received from various customers WITHOUT WIRE on them into our Company and a certain number being sent out to customers WITH WIRE on them.

We have the following tables:

CUSTOMERS-Holds all of our customers company names and CUST ID.
STANDSIN - with a field called Qty for stands received from customers
STANDSOUT- also with a field called Qty for stands shipped out

Customer has a CUST field and is indexed as CUST.
StandsIn and StandOut also have CUST as one of their related fields to the CUSTOMER table.

I want to end up with a report GROUPED by CUSTOMERS showing stands Received and Stands shipped out as followed:

NAME OF CUSTOMER   QTY Recv'd    QTY Sent Out   Difference (Recv'd-Shipped)
CUSTOMER_A         13            23             -10
CUSTOMER_B         98            58             40
CUSTOMER_C         112           140            -28
CUSTOMER_D         1000          980            20

What we are trying to do is to focus on the customers who have not been returning our stands, so that if we see a negative number, we know that that customer has not been returning our WIRE STANDS and can then focus on them.

I tried a regular UNION SQL Statement, but that didn't seem right. Would this require more of a LEFT OUTER JOIN type of statement?