SQL- get data from two tables in different columns without using unions - sql

Question

I have a table STOCK that looks like this:
PRODUCT SALES_CODE STOCK_1 STOCK_2 STOCK_3
-----------------------------------------------------
A 6-10 0 1 2
There are many STOCK_X buckets but for simplicity's sake, I've excluded.
Now I have another table SIZE_GRID:
SALES_CODE SIZE_1 SIZE_2 SIZE_3
--------------------------------------
6-10 6 8 10
As you might have guessed, these are stock on hand for a certain product, by size.
I need to get the STOCK values from the first table, and the size from the second table.
Originally, I was doing the following
SELECT
STOCK.PRODUCT,
SIZE_GRID.SIZE_1,
STOCK.STOCK_1
FROM
STOCK
INNER JOIN
SIZE_GRID ON
SIZE_GRID.SALES_CODE = STOCK.SALES_CODE
UNION ALL
SELECT
STOCK.PRODUCT,
SIZE_GRID.SIZE_2,
STOCK.STOCK_2
FROM
STOCK
INNER JOIN
SIZE_GRID ON
SIZE_GRID.SALES_CODE = STOCK.SALES_CODE
UNION ALL
SELECT
STOCK.PRODUCT,
SIZE_GRID.SIZE_3,
STOCK.STOCK_3
FROM
STOCK
INNER JOIN
SIZE_GRID ON
SIZE_GRID.SALES_CODE = STOCK.SALES_CODE
I have around 40 STOCK_X that I need to retrieve, so wandering if there is a much easier way to do this? Preferably I want to use pure SQL and no UDF/SP's.
http://sqlfiddle.com/#!6/f323e

Answer 1

If you are on SQL Server 2008 or later version, you could try the following method (found here):
SELECT
STOCK.PRODUCT,
X.SIZE,
X.STOCK
FROM
STOCK
INNER JOIN
SIZE_GRID ON
SIZE_GRID.SALES_CODE = STOCK.SALES_CODE
CROSS APPLY (
VALUES
(SIZE_GRID.SIZE_1, STOCK.STOCK_1),
(SIZE_GRID.SIZE_2, STOCK.STOCK_2),
(SIZE_GRID.SIZE_3, STOCK.STOCK_3)
) X (SIZE, STOCK)
;
With a small tweak you could make it work in SQL Server 2005 as well:
SELECT
STOCK.PRODUCT,
X.SIZE,
X.STOCK
FROM
STOCK
INNER JOIN
SIZE_GRID ON
SIZE_GRID.SALES_CODE = STOCK.SALES_CODE
CROSS APPLY (
SELECT SIZE_GRID.SIZE_1, STOCK.STOCK_1
UNION ALL
SELECT SIZE_GRID.SIZE_2, STOCK.STOCK_2
UNION ALL
SELECT SIZE_GRID.SIZE_3, STOCK.STOCK_3
) X (SIZE, STOCK)
;
However, if you are using an even earlier version, this might be of help:
SELECT
STOCK.PRODUCT,
SIZE = CASE X.N
WHEN 1 THEN SIZE_GRID.SIZE_1
WHEN 2 THEN SIZE_GRID.SIZE_2
WHEN 3 THEN SIZE_GRID.SIZE_3
END,
STOCK = CASE X.N
WHEN 1 THEN STOCK.STOCK_1
WHEN 2 THEN STOCK.STOCK_2
WHEN 3 THEN STOCK.STOCK_3
END,
FROM
STOCK
INNER JOIN
SIZE_GRID ON
SIZE_GRID.SALES_CODE = STOCK.SALES_CODE
CROSS JOIN (
SELECT 1
UNION ALL
SELECT 2
UNION ALL
SELECT 3
) X (N)
;
Although the last two options use UNION ALL, they are combining single rows only, not entire subsets

Answer 2

Consider normalizing the table. Instead of a repeating column:
PRODUCT SALES_CODE STOCK_1 STOCK_2 STOCK_3
Use a normalized table:
PRODUCT SALES_CODE STOCK_NO STOCK
And the same for the SIZE_GRID table:
SALES_CODE SIZE_NO SIZE
Now you can query without the need to list 40 columns:
select *
from STOCK s
join SIZE_GRID sg
on sg.SALES_CODE = s.SALES_CODE
and sg.SIZE_NO = s.STOCK_NO

Answer 3

Here are some alternatives you can use:
Execute each SQL separately and merge and sort the result sets within your program
Join the tables.
Use a scalar subquery.
select
select col1, col2, col3 from Table_1 q1,
select col1, col2,
col3 from Table_2 q2 from dual;
Try UNION using FULL OUTER JOIN with the NVL function: It is suggested that this has faster performance than the UNION operator.
select
empno,
ename,
nvl(dept.deptno,emp.deptno) deptno, dname from emp
full outer join
dept
on
(emp.deptno = dept.deptno)
order by 1,2,3,4;