MySQL:4个表"has-many-through"加入? [英] MySQL: 4 Table "has-many-through" Join?

问题描述

比方说，我有以下4个表(例如，为了方便起见):所有者，卡车，盒子，苹果.

Let's say I have the following 4 tables (for examples' sake): Owners, Trucks, Boxes, Apples.

一个所有者可以有很多卡车，一辆卡车可以有很多盒子，一个盒子可以有很多苹果.

An owner can have many trucks, a truck can have many boxes and a box can have many apples.

所有者有一个ID.卡车有一个ID和owner_id.盒子有一个id和truck_id.苹果有一个id和box_id.

Owners have an id. Trucks have an id and owner_id. Boxes have an id and truck_id. Apples have an id and box_id.

比方说，我想让所有ID为34的所有者拥有"苹果.因此，我想让所有者34拥有的卡车中的盒子中的所有苹果都拥有.

Let's say I want to get all the apples "owned" by an owner with id = 34. So I want to get all the apples that are in boxes that are in trucks that owner 34 owns.

如果您将拥有4个表，则每个表仅引用其直接父"表，则将具有层次结构".在满足其他3个表的条件的同时，如何快速筛选框?

There is a "hierarchy" if you will of 4 tables that each only has reference to its direct "parent". How can I quickly filter boxes while satisfying conditions across the other 3 tables?

我希望这有些道理.

谢谢.

推荐答案

select a.* 
from Trucks t
inner join Boxes b on t.id = b.truck_id
inner join Apples a on b.id = a.box_id
where t.owner_id = 34

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