Extract Specific Data After a aggregation (Or any other solution for the desired result) - sql-server

Question

I want to select the Total "sales" of a specific "main_category" for the year 2016
(main categories that don't have sales in that year should appear as zero)
I have managed to select the "sales" of a specific "main category" with all the other "main_categories" (that doesn't have any sales) appearing as zero using below query:
SELECT
mc.name,
ISNULL(SUM(s.no_of_units * b.unit_price),0) AS tCatSales
FROM Sales s
INNER JOIN Invoice i ON i.invoice_ID = s.invoice_id
INNER JOIN Inventory inv ON inv.inventory_ID = s.inventory_ID
INNER JOIN Batch b ON b.batch_ID = inv.batch_ID
INNER JOIN Products p ON p.product_id = b.product_ID
INNER JOIN Category c ON c.category_ID = p.category_id
RIGHT JOIN Main_Category mc ON mc.cat_id = c.main_category
--WHERE YEAR(i.trans_date) = 2016
GROUP BY mc.name
--HAVING YEAR(i.trans_date)=2016
but when I try to further segregate it for year 2016 ONLY either by WHERE clause or HAVING clause, it stops showing "main_category" names that have zero sales in the year.
One thing that I can think of is to give the query invoices only from 2016
which I tried to did by doing something like,
Replacing the line:
INNER JOIN Invoice i ON i.invoice_ID = s.invoice_id
with:
INNER JOIN Invoice i ON i.invoice_ID IN (SELECT invoice_id FROM Invoice in2 WHERE Year(in2.trans_date)=2016)
which did display the categories with zero values but with increased the calculated Sales Amount (from 2069 to something 203151022.75).
I understand this addition is somewhat illogical and disrupts the whole Inner Joins but so far these are the closest thing I can think of or find on the web.
I REPEAT the desired result is: main categories that don't have sales in that year should appear as zero with the year given year/month/date

Answer 1

As Sean and Eli mentioned, RIGHT JOIN is not recommended, you may change it to LEFT JOIN, OR use subquery like this:
SELECT
mc.name,
tCatSales = ISNULL(
(
SELECT
SUM(s.no_of_units * b.unit_price) AS tCatSales
FROM Sales s
INNER JOIN Invoice i ON i.invoice_ID = s.invoice_id
INNER JOIN Inventory inv ON inv.inventory_ID = s.inventory_ID
INNER JOIN Batch b ON b.batch_ID = inv.batch_ID
INNER JOIN Products p ON p.product_id = b.product_ID
INNER JOIN Category c ON c.category_ID = p.category_id
WHERE mc.cat_id = c.main_category
AND YEAR(i.trans_date) = 2016
) , 0)
FROM Main_Category mc

Answer 2

try this:
WHERE ISNULL(YEAR(i.trans_date), 1) = 2016
if you put simple equals conditions on outer join it will eliminate nulls, which give zero-valued rows you desire.
Also note that something like:
WHERE YEAR(i.trans_date) = 2016
is not sargable, see here