How to insert data from 4 queries into one table when the 4 queries have data that are not unique?

Question

to be more clear I have these kind of data.

Query 1) Data from 2016

Item       Price        Quantity

Shoe        20             10
Shoe        30            


        

Answer 1

Try use it, It includes GROUP BY the items and the prices.

SELECT Item,
Price,
SUM(Quantity2016),
SUM(Quantity2017),
...
FROM
(
    --query 1:

    SELECT Item, 
    Price,
    Quantity AS Quantity2016,
    NULL AS Quantity2017  
    NULL AS Quantity2018   
    NULL AS Quantity2019
    FROM 2016

    UNION ALL

    --query 2:

    SELECT Item, 
    Price,
    NULL AS Quantity2016,
    Quantity AS Quantity2017  
    NULL AS Quantity2018   
    NULL AS Quantity2019
    FROM 2017

    UNION ALL

    --query 3:

    SELECT Item, 
    Price,
    NULL AS Quantity2016,
    NULL AS Quantity2017  
    Quantity AS Quantity2018   
    NULL AS Quantity2019
    FROM 2018

    UNION ALL
    ...

)A
GROUP BY Item, Price