Question

I’m lost with an MySQL query (running MySQL 5.0.88)

I have two tables, one with products from different brands, the other one with applications (= applications filter products, so not every application displays every product).

I’m trying to query to get a list of brands depending on the application the user is running like so:

SELECT    p.brand_name
        , p.id
        , p.seller_id
        , a.seller_id
        , a.info  
        , a.name
        , a.application_match_keys  

    FROM  applications AS a 
    LEFT JOIN products AS p
        ON a.seller_id = p.seller_id    
        AND p.brand_name IN ( <<QueryString: application_match_keys>> )

    WHERE  p.active = "1"
    AND    a.seller_id = "2222222222222"

    GROUP BY p.brand_name
    ORDER BY p.brand_name ASC 

Problem is, once I do the left join I’m no longer getting correct results, so for example:

=== products ===
id        brand_name  seller_id
123       A           John
111       A           John
124       A           John
999       B           John
xx1       C           John

=== applications ===
name    seller_id   info  application_match_keys
red     John        foo   A
blue    John        bar   B,C

If the user is in application A, his brand list should only include brands from active products with corresponding match_keys (= A), so I would expect the query to return

p.brand_name  application   info
A             red           foo

But I’m always getting the correct brand name with mis-matched application data like so:

p.brand_name  application   info
A             blue          bar

Question:
Is there a way to query this in a single query, or do I have to query active products' brands with matching application key first and then loop/query again to get the application data I need? Must be possible in a single query, too?

Thanks for help!

EDIT:
Got it. This is how it works:

SELECT    p.brand_name
        , p.id
        , p.seller_id
        , a.seller_id
        , a.info  
        , a.name
        , a.application_match_keys 

FROM  applications AS a 
LEFT JOIN products AS p
    ON a.seller_id = p.seller_id
    AND p.brand_name IN ( <<QueryString: application_match_keys>> )
    AND FIND_IN_SET( a.application_match_keys, <<QueryString: application_match_keys>>) <> 0    

WHERE  p.active = "1"
AND    a.seller_id = "2222222222222"

GROUP BY p.brand_name
ORDER BY p.brand_name ASC 

Thank you very much!

Answer 1

how about using FIND_IN_SET?

AND FIND_IN_SET(p.brand_name, a.application_match_keys) <> 0

• FIND_IN_SET