Question

So i have a database with a few tables. the main is Plant. I also have a PlantEffects table that has plant_id, effect_id. What I need to do select Plants but with the top 5 PlantEffects by count on PlantEffects.effect_id. So it would come out as

|ID|NAME|top_effect_ids|
|1 |abc |1,4,5,6,7     |
|2 |def |3,2,9,7,5     |

Answer 1

If I understand your question correctly, you want to get the top five effect_ids (by count) into a CSV list.

You can do something like this:

SELECT 
    a.id, 
    a.name, 
    SUBSTRING_INDEX(GROUP_CONCAT(b.effect_id ORDER BY b.effectcnt DESC), ',', 5) AS top_effect_ids
FROM 
    plants a
INNER JOIN
(
    SELECT plant_id, effect_id, COUNT(1) AS effectcnt
    FROM planteffects
    GROUP BY plant_id, effect_id
) b ON a.id = b.plant_id
GROUP BY 
    a.id, a.name