mysql，根据类别的UUID获取产品的总重量

Question

I am attempting to aquire the total weight of gear, and the name of the category, based on the category that the gear is listed within.

I have three tables of concern.

'gear' (which holds the information about each piece of gear, including the weight) and it has a UUID and the weight field is called "Weight"

'gear_list' (which holds the name of the category in a field called "Subject" and has its own UUID)

'gear_list_items' (which contains the GearUUID, GearListUUID, CategoryUUID)

What I am able to pass to the php script is the GearListUUID.

So what I am needing here is a way to query and have results such as this:

CategoryName, 268 (weight/grams) AnotherCategoryName, 485 (weight/grams) AnotherCategoryName, 1028 (weight/grams) AnotherCategoryName, 768 (weight/grams) AnotherCategoryName, 448 (weight/grams)

I suspect I may need to post some schema dump, but if anybody has knowledge of how to do this before I go and post all that, it would be highly appreciated.

Answer 1

It's hard to tell for sure without seeing actual table schemas and sample data but you want something like

SELECT l.Subject, SUM(g.Weight) Weight
  FROM gear_list l JOIN gear_list_items i
    ON l.GearListUUID = i.GearListUUID JOIN gear g
    ON i.GearUUID = g.GearUUID
-- WHERE l. GearListUUID = ?
 GROUP BY l.Subject