Show Items even if 0 rows with group by - mysql

Question

I'm trying to get the query below to show for each item for each store the amount of each of 4 items we have.
It works great, and I created the temporary table to try to increase speed but my problem is that if the table has no rows for a certain product that product does not show up at all.
I'd like to show all four products(prodNo) regardless of if there is actually any of rows for that specific store.
I researched this site and could not find something similar enough for me to figure it out.
CREATE TEMPORARY TABLE IF NOT EXISTS temp_invoice_dates AS
(
SELECT Invoice_detail.del_date,invoice_Detail.StoreNo,mast_stores.SDesc, invoice_Detail.ProdNo,sold_qty,retn_price,retn_qty,sold_price FROM Invoice_detail
LEFT JOIN mast_stores on invoice_detail.StoreNO=mast_stores.Snum
LEFT JOIN invoice on invoice_detail.Del_Date=invoice.Del_Date and invoice_detail.Invoice_No=invoice.Invoice_No
WHERE Cnum IN ('200','210') AND invoice_detail.Del_Date >= "2016-03-01" AND invoice_detail.Del_Date < "2016-04-01"
);
SELECT
temp_invoice_dates.StoreNo,
temp_invoice_dates.SDesc,
DATE_FORMAT(temp_invoice_dates.Del_Date,'%Y') as Year,
DATE_FORMAT(temp_invoice_dates.Del_Date,'%M') as Month,
temp_invoice_dates.ProdNo,
mast_items.IDesc,
SUM(sold_qty) as TotalIn,
SUM(retn_qty) as TotalOut,
ROUND(SUM((sold_qty*sold_price)-(retn_qty*retn_price)),2) as NetSales,
CONCAT(ROUND(SUM(retn_qty)/SUM(sold_qty),2)*100,'%') as StalePerc
FROM mast_Items
LEFT JOIN temp_invoice_dates on temp_invoice_dates.ProdNo=mast_items.Inum
WHERE mast_items.Inum in ('3502','3512','4162','4182')
GROUP BY temp_invoice_dates.StoreNo, ProdNo
ORDER BY temp_invoice_dates.StoreNo, ProdNo;
Drop table temp_invoice_dates;
Results are similar to:
StoreNo Product Count....
1 1 1
1 2 5
1 3 2
1 4 1
2 1 14
2 2 1
2 4 4
3 2 33
3 3 3
Where as I'd like it to be
StoreNo Product Count ....
1 1 1
1 2 5
1 3 2
1 4 1
2 1 14
2 2 1
2 3 0
2 4 4
3 1 0
3 2 33
3 3 3
3 4 0

Answer 1

Something like this should work.
SELECT sp.StoreNo, sp.ProdNo
, ...stuff...
, sp.IDesc, sp.SDesc
, ...more stuff...
FROM (
SELECT i.Inum AS ProdNo, s.Snum AS StoreNo
, i.IDesc, s.SDesc
FROM mast_Items AS i, mast_stores AS s
WHERE i.Inum IN ('3502','3512','4162','4182')
) AS sp
LEFT JOIN temp_invoice_dates AS tid
ON sp.ProdNo = tid.ProdNo
AND sp.StoreNo = tid.StoreNo
GROUP BY sp.StoreNo, sp.ProdNo
ORDER BY sp.StoreNo, sp.ProdNo
;
Normally I recommend against cross joins (as seen in the subquery) but in this case it is exactly what is needed. If the query is slow, you can instead insert the subquery results into a temp table beforehand, index that, and then use the temp table in place of the subquery.
(Edit: should use sp fields when available for grouping and results)