Sum values ​for each unique ID

I have a query that makes a set of relationships and gives me a number of rows that can be repeated for the same ID_PROD. The THEORETICAL_WEIGHT column will always be the same for a unique ID_PROD, and the REAL_WEIGHT column informs the actual weight that the product had when it was produced. This is my query:

    SELECT 
        A.ID_PROD,  A.REAL_WEIGHT, B.THEORETICAL_WEIGHT, 
        A.REAL_WEIGHT * B.THEORETICAL_WEIGHT AS Stock
    FROM 
        Table_A A,   
        Table_B B
    WHERE 
    B.ID_PROD = A.ID_PROD;

To find the weight we use, we need to multiply each product’s real weight value by the theoretical weight. My query above brings me values ​​like the ones below.

ID_PROD | REAL_WEIGHT | THEORETICAL_WEIGHT | Stock
 P01         1,5               3              4,5
 P01         0,3               3              0,9
 P01         5,1               3              15,3
 P02         2,1               2              4,2
 P02          3                2              6        
 P03          4                6              24

However, I want to improve this query, in a way that it only brings me a single row for each ID_PROD and in it, it already shows me the sum of the real weight of all the products of that ID_PROD, the theoretical weight value of that ID_PROD and the weight multiplication (real * theoretical weight). The expected result would be something like this:

ID_PROD | REAL_WEIGHT | THEORETICAL_WEIGHT | Stock
   P01         6,9               3            20,7
   P02         2,1               2            10,2      
   P03          4                6            24

>Solution :

Aggregation, along with group by clause that contains columns that aren’t aggregated:

SELECT
    a.id_prod,
    SUM(a.real_weight) AS real_weight,
    b.theoretical_weight,
    SUM(a.real_weight * b.theoretical_weight) AS stock
FROM table_a a JOIN table_b b ON b.id_prod = a.id_prod
GROUP BY
    a.id_prod,
    b.theoretical_weight;