Question :
I have a product table where the value of two columns can imply either one or two actual product results. If column X = 1 AND Y = 0 return one result, if X = 0 and Y = 1 return one result, if X = 1 AND Y = 1 then return two results.
I want to write a query that will generate two row results for a single row based on the above rule. How can this be done with a SQL query? Is a UNION the only way?
[EDIT based on comment]
TABLE: PRODUCT
ProductId | ABR | UBR
1 | 1 | 1
2 | 1 | 0
3 | 0 | 1
4 | 1 | 1
5 | 1 | 1
I want a SELECT statement that will generate 8 results from this set. Basically one result for each instance of either ABR or UBR = 1.
So I would like my result to be:
ProductId | Edition
1 | ABR
1 | UBR
2 | ABR
3 | UBR
4 | ABR
4 | UBR
5 | ABR
5 | UBR
I know I can achieve this using a UNION but I was looking for something more elegant.
Answer :
I’d use UNPIVOT
for this unless abr
and ubr
are both indexed and a relatively low proportion contain the value 1
.
(Borrowing JNK’s table variable)
SELECT id,
Edition
FROM @prod
UNPIVOT (V FOR Edition IN (abr,ubr)) AS Unpvt
WHERE V = 1
UNION
does make sense.
You can put the UNION
in a subquery which will neaten it up some:
DECLARE @prod TABLE (id int, abr int, ubr int)
INSERT INTO @prod
VALUES
(1 , 1 , 1),
(2 , 1 , 0),
(3 , 0 , 1),
(4 , 1 , 1),
(5 , 1 , 1)
SELECT id, 'ABR' as Ed
FROM @prod
WHERE abr = 1
UNION ALL
SELECT id, 'UBR' as Ed
FROM @prod
WHERE ubr = 1
ORDER BY id
You could also do an UNPIVOT
I think but for this simple use case a UNION
seems most efficient.