I'm using this query to collate two sets of results but I now need to use JOIN instead of UNION to get the second part of the data from another table.
However I need quite a lot of fields and can't seem to find a way to maintain the use of SELECT * when using JOIN.
mysql_query("SELECT * FROM table.products WHERE category='$cat' GROUP BY product_id ORDER BY id UNION ALL SELECT * FROM table.products WHERE type='red' GROUP BY product_id ");
Table - products
product_id | title | category | id
0 one home 10
1 two home 11
1 two - a home 12
2 three work 13
Table - product_details
product_id | type | size |
0 blue S
1 blue M
1 red L
Ultimately I need to list every product in the first table for a given category eg home, as there is sometimes two entries or more for a single product id, I need to only select one row for each product id value. I also need to join the second table so I can get the size info, however I must be able to get the size info by preferring a type eg red.
So for this example I would get a list like:
product_id | title | category | type | size
0 one home blue S
1 two home red L
This excludes product_id 2 as it's not in the home category, the first entry for product_id equaling 1 is selected because of the GROUP BY and ORDER BY and the information on size for product_id 1 is L because it is of type red not blue.
Your query can be simplified like below since you are using the same table table.products
. Not sure why you need to UNION
them.
SELECT * FROM table.products
WHERE category='$cat'
and type='red'
GROUP BY product_id
EDIT:
With your edited post, the query should look like
select p.product_id,p.title,p.category,q.type,q.size
from products p join product_details q
on p.product_id = q.product_id
where p.category = 'home'
and q.type = 'red'
Assuming you are using MySQL, you want a join with an aggregation or aggressive filtering. Here is an example using join
and aggregation
:
select p.product_id, p.title, p.category,
substring_index(group_concat(pd.type order by pd.type = 'red' desc, pd.type), ',', 1) as type,
substring_index(group_concat(pd.size order by pd.type = 'red' desc, pd.type), ',', 1) as size
from products p join
product_details pd
on p.product_id = qpd.product_id
where p.category = 'home'
group by p.product_id;
The expression substring_index(group_concat(. . .))
is choosing one type
(and one size
) with precedence given to the red
type.
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