How take the defference between sum of column values?

Question

I have two simple tables. tbl_purchased and tbl_sold

tbl_purchased

col_item_name col_no_of_items
Fan                         5
Builb                       5
Oven                        5
Fan                         2
Builb                       2

tbl_sold

col_item_name col_no_of_items
Fan                         3
Oven                        1

I need to take

1. SUM of items purchased, GROUP BY item name.
2. SUM of items sold, GROUP BY item name.

I can do that using following queries separately.

SELECT col_item_name, SUM(col_no_of_items)
FROM tbl_purchased
GROUP BY col_item_name;

and

SELECT col_item_name, SUM(col_no_of_items)
FROM tbl_sold
GROUP BY col_item_name;

now I need to take the current stock.

That means, (SUM of purchased items - SUM of sold items) GROUP BY item name.

Can I do that using SINGLE sql query?

Answer 1

Try something like bellow (might need to adjust it though):

SELECT p.col_item_name, SUM(p.col_no_of_items) - SUM (s.col_no_of_items)
FROM tbl_purchased p
left join tbl_sold s on p.col_item_name=s.col_item_name
GROUP BY p.col_item_name;

Answer 2

Or you could use

SELECT col_item_name, SUM(no_purchased) - SUM(no_sold) AS item_stock
FROM
   (SELECT col_item_name, col_no_of_items AS no_purchased, 0 AS no_sold
    FROM tbl_purchased
    UNION ALL
    SELECT col_item_name, 0 AS no_purchased,col_no_of_items AS no_sold)
GROUP BY col_item_name

Answer 3

This perfectly work for you

SELECT p. name , ((SELECT SUM(NO) FROM purcahse WHERE name =p.name)-(SELECT COALESCE(SUM(NO),0) FROM sell WHERE name =s.name)) remaining FROM purcahse p LEFT JOIN sell s ON p.name=s.name GROUP BY p.name;

enjoy thanks :)

Answer 4

Suggestion: join your first table expression (need to give the summarization a name eg col_no_of_items_purchased ) to tbl_curent_stock , then do simple arithmetic. You should also consider items that haven't been purchased by anti-joining. Then UNION the two together:

SELECT col_item_name,
       col_no_of_items - col_no_of_items_purchased AS col_no_of_items
FROM tbl_curent_stock
     NATURAL JOIN
     ( SELECT col_item_name,
              SUM(col_no_of_items) AS col_no_of_items_purchased
         FROM tbl_purchased
        GROUP
           BY col_item_name ) AS t
UNION
SELECT col_item_name, col_no_of_items
  FROM tbl_curent_stock
 WHERE col_item_name NOT IN ( SELECT col_item_name
                                FROM tbl_purchased );