Question

I have a database that I’ve inherited and need to create a query that generates all possible variations of a SKU. One table has the “base” SKU and the other table has all the SKU modifiers.

Example

Base SKU: MARIN could be modified into

MARINR15 MARINB15 MARING15
MARINR17 MARINB17 MARING17
MARINR19 MARINB19 MARING19
MARINR20 MARINB20 MARING20

Base SKU

ProductID   SKU
----------- ---------------
532         MARIN

SKU Modifiers

ProductID   OptionName           OptionValue              SkuModifier
----------- -------------------- ------------------------ -----------
532         Color                Red                      R
532         Color                Green                    G
532         Color                Blue                     B
532         Size                 17"                      17
532         Size                 15"                      15
532         Size                 19"                      19
532         Size                 20"                      20

Answer 1

You can use a recursive solution (and indeed, this is probably the only viable answer). You’d probably save processing if you had a predifined ordering (because at the moment the only way I can think to do this is text concatenation).

Here is a general solution that should get you your needed results.
Note that this was written and run on DB2 (iSeries) – you may need to adjust it for SQL Server.

WITH Combined(productId, options, combination, level) as (
              SELECT productId, optionName, skuModifier, 1
              FROM #Modifiers
              UNION ALL
              SELECT a.productId, a.options || b.optionName,
                     a.combination || b.skuModifier, a.level + 1
              FROM Combined as a
              JOIN #Modifiers as b
              ON b.productId = a.productId
              AND a.options not like ('%' || b.optionName || '%')),
     Option_Count(productId, count) as (SELECT productId, COUNT(DISTINCT optionName)
                                        FROM #Modifiers
                                        GROUP BY productId)
SELECT a.sku || COALESCE(b.combination, '')
FROM #Base as a
LEFT JOIN (Combined as b
           JOIN Option_Count as c
           ON c.productId = b.productId
           AND c.count = b.level)
ON b.productId = a.productId)

Which yields:

MARIN17R        
MARIN15R        
MARIN19R        
MARIN20R        
MARIN17G        
MARIN15G        
MARIN19G        
MARIN20G        
MARIN17B        
MARIN15B        
MARIN19B        
MARIN20B        
MARINR17        
MARING17        
MARINB17        
MARINR15        
MARING15        
MARINB15        
MARINR19        
MARING19   
MARINB19   
MARINR20   
MARING20   
MARINB20

Personally, though, I think I’d try to get some sort of ordering established – this would at least allow you to knock out dealing with optionName (although in that case you may want to further normalize the tables).
Please note that the CTE Option_Count is being used to restrict results to ‘full-length’ combinations – permutations where all the options are used, rather than just some of them.