如何在嵌套集中定位特定 level2 节点的特定子节点

Question

我有一个标准的嵌套集模型，每个节点都有名称、lft 和 rgt 属性。

我可以使用以下方法找到特定员工的上级：

SELECT P2.* FROM Personnel AS P1, Personnel AS P2
WHERE P1.lft BETWEEN P2.lft AND P2.rgt
AND P1.name = "Bob"
ORDER BY P2.lft

我也可以通过添加limit&offset来找到level2 manager：

SELECT P2.* FROM Personnel AS P1, Personnel AS P2
WHERE P1.lft BETWEEN P2.lft AND P2.rgt
AND P1.name = "Bob"
ORDER BY P2.lft
LIMIT 2 OFFSET 1

在某些情况下，我可能有多个名为“Bob”的员工在不同的二级经理手下工作。二级经理名称是唯一的。

我需要一个查询来返回名为“Susan”的二级经理的所有名为“Bob”的员工。

编辑：我的查询只需要返回在“玛丽”下工作的“鲍勃”，因为他是唯一一个拥有名为“苏珊”的二级经理。

   Big Boss
   /      \
Brian   Susan
  |       |
Susan   Mary
  |       |
 Bob     Bob

Answer 1

输入数字：

  1 Big Boss 14
   /        \
2 Brian 7  8 Susan 13
  |           |
3 Susan 6  9 Mary 12
  |           |
4 Bob 5    10 Bob 11

如果我们可以指定我们知道它是8 的“Susan”，那么：

SELECT employee.* 
FROM Personnel AS employee
inner join Personnel AS manager on employee.lft BETWEEN manager.lft
                                                    AND manager.rgt
WHERE 
  employee.name = 'Bob'
  and manager.name = 'Susan'
  and manager.lft = 8
ORDER BY employee.lft

否则，我认为您需要了解有关记录的更多信息，才能指定您所说的经理。

编辑：使查询更复杂一点，我使用来自this article 的建议计算了深度。 fiddle 也可以正常工作。

select
  employee.*
from
  Personnel employee
  inner join 
    (SELECT node.name, node.lft, node.rgt, (COUNT(parent.name) - 1) AS depth
     FROM Personnel AS node
     inner join Personnel AS parent on node.lft BETWEEN parent.lft AND parent.rgt
     GROUP BY node.name, node.lft, node.rgt) as manager
                 on employee.lft between manager.lft and manager.rgt    
where
  employee.name = 'bob'
  and manager.name = 'susan'
  and manager.depth = 1