sql query to create columns with arithmetic expressions - sql-server

Question

I have my sql tables and query as shown below :
CREATE TABLE #ABC([Year] INT, [Month] INT, Stores INT);
CREATE TABLE #DEF([Year] INT, [Month] INT, SalesStores INT);
CREATE TABLE #GHI([Year] INT, [Month] INT, Products INT);
INSERT #ABC VALUES (2013,1,1);
INSERT #ABC VALUES (2013,1,2);
INSERT #ABC VALUES (2013,2,3);
INSERT #DEF VALUES (2013,1,4);
INSERT #DEF VALUES (2013,1,5);
INSERT #DEF VALUES (2013,2,6);
INSERT #GHI VALUES (2013,1,7);
INSERT #GHI VALUES (2013,1,8);
INSERT #GHI VALUES (2013,2,9);
INSERT #GHI VALUES (2013,3,10);
My current query is
SELECT T.[Year],
T.[Month]
-- select the sum for each year/month combination using a correlated subquery (each result from the main query causes another data retrieval operation to be run)
,
(SELECT SUM(Stores)
FROM #ABC
WHERE [Year] = T.[Year]
AND [Month] = T.[Month]) AS [Sum_Stores],
(SELECT SUM(SalesStores)
FROM #DEF
WHERE [Year] = T.[Year]
AND [Month] = T.[Month]) AS [Sum_SalesStores],
(SELECT SUM(Products)
FROM #GHI
WHERE [Year] = T.[Year]
AND [Month] = T.[Month]) AS [Sum_Products]
FROM (
-- this selects a list of all possible dates.
SELECT [Year],
[Month]
FROM #ABC
UNION
SELECT [Year],
[Month]
FROM #DEF
UNION
SELECT [Year],
[Month]
FROM #GHI) AS T;
Which returns
+------+-------+------------+-----------------+--------------+
| Year | Month | Sum_Stores | Sum_SalesStores | Sum_Products |
+------+-------+------------+-----------------+--------------+
| 2013 | 1 | 3 | 9 | 15 |
| 2013 | 2 | 3 | 6 | 9 |
| 2013 | 3 | NULL | NULL | 10 |
+------+-------+------------+-----------------+--------------+
What I want to do is to add two more columns to my query which shows
Sum_SalesStores/Sum_Products & Sum_SalesStores/Sum_Stores per each month and then sort the query based on the two expressions. Can anyone tell me how its possible ?

Answer 1

One way would just be to chuck your entire existing query into a CTE then you can select from that and perform the calculations.
;WITH CTE
AS (
/*Paste your existing query*/
)
SELECT *,
Sum_SalesStores / Sum_Products AS Foo,
Sum_SalesStores / Sum_Stores AS Bar
FROM CTE
ORDER BY Foo,
Bar

Answer 2

I re-factored your code a bit to place the core of the logic in the FROM statement.
SELECT Dates.[Year]
,Dates.[Month]
,SumStores
,SumSalesStores
,SumProducts
,SumSalesStores/SumProducts
,SumSalesStores/SumStores
FROM
(
-- This selects a list of all possible dates.
SELECT [Year],[Month] FROM ABC
UNION SELECT [Year],[Month] FROM DEF
UNION SELECT [Year],[Month] FROM GHI
) AS Dates
Left Join
(
SELECT [Year]
,[Month]
,SumStores = Sum(Stores)
FROM ABC
GROUP BY [Year]
,[Month]
) As Stores
On Dates.[Year] = Stores.[Year]
And Dates.[Month] = Stores.[Month]
Left Join
(
SELECT [Year]
,[Month]
,SumSalesStores = Sum(SalesStores)
FROM DEF
GROUP BY [Year]
,[Month]
) As SalesStores
On Dates.[Year] = SalesStores.[Year]
And Dates.[Month] = SalesStores.[Month]
Left Join
(
SELECT [Year]
,[Month]
,SumProducts = Sum(Products)
FROM GHI
GROUP BY [Year]
,[Month]
) As Products
On Dates.[Year] = Products.[Year]
And Dates.[Month] = Products.[Month]
ORDER BY 1, 2
Here's the SQL Fiddle.