MySQL-列关联/联接

Question

i don't know how to explain my problem so here is an example :

table products

id_product / name_product
1          / aphone
2          / bphone

table tyds, product_tyd = id_product

id_tyd     / product_tyd   /    user_tyd   /   action_tyd    /  data_tyd
11          /      1        /      1        /      5          /   null
12          /      1        /      1        /      8          /   150
13          /      1        /      2        /      3          /   null
14          /      1        /      2        /     -8          /   250
15          /      2        /      3        /      2          /   null
16          /      2        /      3        /      8          /   150
17          /      2        /      2        /      6          /   null
18          /      2        /      2        /      8          /   250

table collections is exactly the same than table tyds but for old lines :

id_collection / product_collection / user_collection / action_collection / data_collection

    1         /      1             /      9          /      5            /   null
    2         /      1             /      9          /     -3            /   null
    3         /      1             /      9          /     -8            /   150

So i'd like to select the lines where - action_collection = 8 OR -8 - action_tyd = 8 OR -8 with for each line the data_tyd AND/OR the data_collection value but only for a specific id_product...

Something like that :

results i'm expecting for a request on an id_product = 1 :

id_product    /    user_x    /   action_x  / data_x
     1        /       1      /       8     /   150
     1        /       2      /      -8     /   250
     1        /       9      /      -8     /   150

So the point is to rely action_tyd AND data_tyd, which i do with CASE in other request and to filter lines no matter which table is in...except that is not the same column name of course...

I hope my example is clear...I'm actually trying to make it in two separate requests. One for table tyds, one for table collections and i think it can be done but one single request could do the job too...

Thanks for your help !

Answer 1

I think you should combine tyds and collections into a single table (with a suitable column to flag from which table each record originates), but as things stand you're simply looking to perform a UNION :

SELECT product_tyd AS id_product,
       user_tyd    AS user_x,
       action_tyd  AS action_x,
       data_tyd    AS data_x
FROM   tyds
WHERE  product_tyd = 1 AND action_tyd IN (-8,8)

UNION ALL

SELECT product_collection,
       user_collection,
       action_collection,
       data_collection
FROM   collections
WHERE  product_collection = 1 AND action_collection IN (-8,8)