Select field based on value in same record - mysql

Question

I want to SELECT a field based on a ID value.
Products
PRODUCT_ID Name
19 Chair
20 Table
Product_fields
ID PRODUCT_ID TYPE DESCRIPTION
1 19 C White
2 19 S Modern
3 20 C Black
4 20 S Classic
I need a result like:
Product Type_C Type_S
Chair White Modern
Table Black Classic
I am able to produce this using two LEFT JOINs on the product_fields table but this slows down the query too much. Is there a better way?

Answer 1

Slows down the query how much? What is acceptable?
If you really don't want to use joins (you must have one join), then use views or nested queries. But I don't think they will be any faster, though you can give it a try.
See views at sqlfiddle
select p.PRODUCT_ID, p.Name, f.CDescription, f.SDescription
from Products p
join(
SELECT PRODUCT_ID, Max( CDescription ) as CDescription,
Max( SDescription ) as SDescription
FROM(
select PRODUCT_ID,
case Type when 'C' then Description end as CDescription,
case Type when 'S' then Description end as SDescription
from Fields
) x
group by PRODUCT_ID
) f
on f.PRODUCT_ID = p.PRODUCT_ID;

Answer 2

The complete statement is:
SELECT
NL.product_name,
PRD.product_sku AS product_sku,
CF.virtuemart_product_id AS virtuemart_product_id,
GROUP_CONCAT(distinct CFA.customsforall_value_name
ORDER BY CFA.customsforall_value_name ASC
separator ' | ' ) AS Name_exp_3,
ROUND((((prices.product_price * CALC.calc_value) / 100) + prices.product_price),
2) AS Prijs,
VMCF_L.custom_value AS latijn,
VMCF_T.custom_value AS THT
VMCF_B.custom_value AS Batch
from j25_virtuemart_products AS PRD
LEFT join j25_virtuemart_product_custom_plg_customsforall AS CF ON CF.virtuemart_product_id = PRD.virtuemart_product_id
join j25_virtuemart_product_prices AS prices ON PRD.virtuemart_product_id = prices.virtuemart_product_id
join j25_virtuemart_calcs AS CALC ON prices.product_tax_id = CALC.virtuemart_calc_id
join j25_virtuemart_products_nl_nl AS NL ON NL.virtuemart_product_id = PRD.virtuemart_product_id
LEFT join j25_virtuemart_product_customfields AS VMCF ON VMCF.virtuemart_product_id = PRD.virtuemart_product_id
LEFT join j25_virtuemart_custom_plg_customsforall_values AS CFA ON CFA.customsforall_value_id = CF.customsforall_value_id
LEFT JOIN j25_virtuemart_product_customfields AS VMCF_L ON VMCF.virtuemart_product_id = VMCF_L.virtuemart_product_id AND VMCF_L.virtuemart_custom_id = 16
LEFT JOIN j25_virtuemart_product_customfields AS VMCF_T ON VMCF.virtuemart_product_id = VMCF_T.virtuemart_product_id AND VMCF_T.virtuemart_custom_id = 3
LEFT JOIN j25_virtuemart_product_customfields AS VMCF_B ON VMCF.virtuemart_product_id = VMCF_B.virtuemart_product_id AND VMCF_B.virtuemart_custom_id = 18
WHERE
PRD.product_sku like '02.%'
group by PRD.virtuemart_product_id
order by NL.product_name;
Where the three SELECT results named 'Latijn', 'THT', and 'Batch' are the ones which I compared earlier as the black/white and classic/modern values.
Hope this makes any sense.
As you can see this involves a Virtuemart installation, so I cannot fiddle about to much with the schema.
When I exclude the bottom 3 JOINS and there related FIELDS, the query takes approx 0,5 seconds. With the JOINS and FIELDS included, the query takes almost 19 seconds.
I have created a view from this complete query which I query from my labeling application.

Answer 3

Thanks everyone! With your input I created:
select
NL.product_nameASproduct_name,
PRD.product_skuASproduct_sku,
CF.virtuemart_product_idASvirtuemart_product_id,
group_concat(distinctCFA.customsforall_value_name
order byCFA.customsforall_value_nameASC
separator ' | ') ASName_exp_3,
round((((prices.product_price*CALC.calc_value) / 100) +prices.product_price),
2) ASPrijs,
f.LatijnASLatijn,
f.THTASTHT,
f.BatchASBatch
from
(((((((j25_virtuemart_productsPRD
left joinj25_virtuemart_product_custom_plg_customsforallCFON ((CF.virtuemart_product_id=PRD.virtuemart_product_id)))
joinj25_virtuemart_product_pricespricesON ((PRD.virtuemart_product_id=prices.virtuemart_product_id)))
joinj25_virtuemart_calcsCALCON ((prices.product_tax_id=CALC.virtuemart_calc_id)))
joinj25_virtuemart_products_nl_nlNLON ((NL.virtuemart_product_id=PRD.virtuemart_product_id)))
left joinj25_virtuemart_product_customfieldsVMCFON ((VMCF.virtuemart_product_id=PRD.virtuemart_product_id)))
left joinj25_virtuemart_custom_plg_customsforall_valuesCFAON ((CFA.customsforall_value_id=CF.customsforall_value_id)))
left joinvw_batch_Latijn_THT_groupedfON ((f.virtuemart_product_id=PRD.virtuemart_product_id)))
where
(PRD.product_skulike '02.%')
group byPRD.virtuemart_product_id
order byNL.product_name``
Which takes 1.4 seconds to execute, a whole lot faster then the 19 seconds I started with.