Question

I’m using this mysql query to pull back a single result, and concatenate the results from a join:

SELECT card_name, GROUP_CONCAT(DISTINCT cat_name SEPARATOR ',') AS catcsv 
FROM  `cards` 
LEFT JOIN card2cat ON cards.cards_id = card2cat.card2cat_card 
LEFT JOIN cats ON card2cat.card2cat_cat = cats.cats_id 
WHERE  `card_id` = 1

This returns:

card_name    catcsv
-----------------------------
Violets      Floral, Occasion

This is perfect for what I need… however I need to get the same results, but for multiple results like so:

SELECT card_name, GROUP_CONCAT(DISTINCT cat_name SEPARATOR ',') AS catcsv 
FROM  `cards` 
LEFT JOIN card2cat ON cards.cards_id = card2cat.card2cat_card 
LEFT JOIN cats ON card2cat.card2cat_cat = cats.cats_id 
LIMIT 0, 10

..but that returns this:

card_name    catcsv
-----------------------------
Violets      Floral, Occasion, Birthday, Down at the Farm, Cats and Dogs, Down at the Yard, Humour, Beach, Coast and Harbour, Gardening

i.e ALL the possible cats 🙁 I’ve tried removing DISTINCT and it’s even worse and returns every category multiple times!

The structure/names I’ve used above are simplified for posting, so pasting a DB structure dump here isn’t too practical, I hope I’ve explained it well enough!?

Answer 1

You are just missing the GROUP BY clause:

SELECT card_name, GROUP_CONCAT(DISTINCT cat_name SEPARATOR ',') AS catcsv 
FROM  `cards` 
LEFT JOIN card2cat ON cards.cards_id = card2cat.card2cat_card 
LEFT JOIN cats ON card2cat.card2cat_cat = cats.cats_id 
GROUP BY card_name
LIMIT 0, 10