如何在单个查询中显示每个月的购买和退货？

Question

I want to show each month purchase and purchase return from two different tables. group by purchase type(or catetype) and month wise.(one year report) what i tried is:

SELECT
    MONTH(p_purch_stock.date) AS mnth_no,
    p_parts.catetype,
    SUM(p_purch_stock.Netamount) AS sale,
    SUM(  p_purch_return.unit_price * p_purch_return.return_qty  ) AS return_amount
FROM
    p_purch_stock
INNER JOIN p_parts ON p_purch_stock.part_no = p_parts.Part_no
INNER JOIN p_purch_return ON p_purch_stock.stock_id=p_purch_return.stock_id
WHERE
    (p_purch_stock.cate_type = 'IMC-imported' OR p_purch_stock.cate_type = 'IMC' OR p_purch_stock.cate_type = 'IMC-Local' ) 
    AND DATE_FORMAT(p_purch_stock.date, '%Y-%m-%d') BETWEEN '2019-01-01' AND '2019-12-31'
    AND DATE_FORMAT(  p_purch_return.datetime,   '%Y-%m-%d'    ) BETWEEN '2019-01-01' AND '2019-12-31'
GROUP BY
    MONTH(p_purch_stock.date),
    p_parts.catetype