Question

I’m trying to unite two tables in MySQL, the query I’m using is:

SELECT qa_invoicesitems.item_code, qa_invoicesitems.item_unitprice,    qa_invoicesitems.item_subtotal, qa_invoicesitems.item_discount, 
qa_invoicesitems.item_total 
FROM qa_invoicesitems   
RIGHT JOIN qa_invoicesitems_returnlog USING (item_code) 
WHERE invoice_code = 17
UNION
SELECT qa_invoicesitems_returnlog.item_code, qa_invoicesitems_returnlog.item_unitprice, qa_invoicesitems_returnlog.item_subtotal, 
qa_invoicesitems_returnlog.item_discount, qa_invoicesitems_returnlog.item_total 
FROM qa_invoicesitems_returnlog 
LEFT JOIN qa_invoicesitems USING (item_code) 
WHERE returnlog_code = 9

But I can not behold the desired result.

A graphical example ..

Anyone have any idea how I can get this result?
NOTE: qa_invoicesitems_returnlog Replaces the data.

The codes: 1234, 1585, 23 are taken from (qa_invoicesitems_returnlog), because they exist in both tables, the rest are simply displayed.

Answer 1

Based upon your comments & your image, I’m going to say you want:

• all the rows in table 2 where qa_invoicesitems_returnlog = 9
• all the rows in table 1 where invoice_code = 17, except for those rows w/ item_id‘s that are already present in the output from table 2.

So, writing that out as a union, give you:

SELECT qa_invoicesitems_returnlog.item_code as item_code, 
       qa_invoicesitems_returnlog.item_unitprice as item_unitprice,
       qa_invoicesitems_returnlog.item_subtotal as item_subtotal,         
       qa_invoicesitems_returnlog.item_discount as item_discount, 
       qa_invoicesitems_returnlog.item_total as item_total 
FROM qa_invoicesitems_returnlog
WHERE qa_invoicesitems_returnlog.returnlog_code = 9
UNION
SELECT qa_invoicesitems.item_code as item_code, 
       qa_invoicesitems.item_unitprice as item_unitprice,
       qa_invoicesitems.item_subtotal as item_subtotal,         
       qa_invoicesitems.item_discount as item_discount, 
       qa_invoicesitems.item_total as item_total 
 FROM qa_invoicesitems   
 WHERE qa_invoicesitems.invoice_code = 17
   AND NOT EXISTS (SELECT * FROM qa_invoicesitems_returnlog qir2
                   WHERE qir2.returnlog_code = 9 
                      and qir2.item_code = qa_invoicesitems.item_code)

The key is the NOT EXISTS clause that excludes from the results from table 1 (qa_invoiceitems) that are already present in the output from table 2 and have a matching item_code.