MySql列出直接和间接子记录

我有一个用于处理传输项的3表DB模式。运输工具可以包含多个箱子和多个项目。除此之外，一个盒子还可以包含多个项目。因此，项目可以直接或间接连接到传输

简化的DDL如下所示：

CREATE TABLE transport (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `transport_number` varchar(50) NOT NULL,
  `transport_date` datetime NOT NULL
)

CREATE TABLE box (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(50) NOT NULL,
  `transport_id` int(11) NOT NULL
)

CREATE TABLE item (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(50) DEFAULT NULL,
  `box_id` int(11) DEFAULT NULL,
  `transport_id` int(11) DEFAULT NULL
)

我尝试实现一个查询，通过框和项目计数选择所有传输。大概是这样的：

预期结果：

TRANSPORT_ID | TRANSPORT_NUMBER | BOX_COUNT | ITEM_COUNT
--------------------------------------------------------
1            | T1               | 2         | 3
2            | T2               | 1         | 2

样本数据

运输：

ID     | TRANSPORT_NUMBER | TRANSPORT_DATE
------------------------------------------
1      | T1               | 2018-11-06
2      | T2               | 2018-11-06

方框：

项目：

---

如果性能不是一个问题，那么这应该是可行的：

SELECT 
  transport.id,
  transport.transport_number,
  (SELECT COUNT(*) FROM box WHERE box.transport_id = transport.id) AS box_count,
  (SELECT COUNT(*) FROM item WHERE item.transport_id = transport.id OR item.box_id IN (SELECT id FROM box WHERE box.transport_id = transport.id)) AS item_count
FROM transport;

---

一个想法是实现所有可用的关系，然后相应地将它们相加：

SELECT 
t.id, 
t.transport_number, 
COUNT(distinct b.id) as box_count, 
COUNT(distinct i.id) + COUNT(distinct i2.id) as item_count
FROM transport t
LEFT JOIN box b ON t.id = b.transport_id
LEFT JOIN item i ON b.id = i.box_id
LEFT JOIN item i2 ON t.id = i2.transport_id
GROUP BY t.id

---

样本数据和期望的结果将非常有用。两个问题对于一个“问题”来说太多了。用样本数据和预期结果编辑了我的问题。

SELECT 
  transport.id,
  transport.transport_number,
  (SELECT COUNT(*) FROM box WHERE box.transport_id = transport.id) AS box_count,
  (SELECT COUNT(*) FROM item WHERE item.transport_id = transport.id OR item.box_id IN (SELECT id FROM box WHERE box.transport_id = transport.id)) AS item_count
FROM transport;

SELECT 
t.id, 
t.transport_number, 
COUNT(distinct b.id) as box_count, 
COUNT(distinct i.id) + COUNT(distinct i2.id) as item_count
FROM transport t
LEFT JOIN box b ON t.id = b.transport_id
LEFT JOIN item i ON b.id = i.box_id
LEFT JOIN item i2 ON t.id = i2.transport_id
GROUP BY t.id