Question

假设我们有一个经典的'经理ID'递归关系表：

用户 user_id int manager_id int（指user_id）

如果您在表中随机选择2行 - 或2个节点 - 您如何找到最低级别的共同祖先？我的平台是SQL Server 2005（Transact-SQL），但任何符合ANSI标准的SQL也可以工作......

Answer 1

对Quassnoi的回答进行了一些小编辑，它的确有效：

WITH
    hier1 (id, parent) AS (
    SELECT      id, parent
    FROM        table
    WHERE       id = @user1
    UNION ALL
    SELECT      id, parent
    FROM        table l, hier1 h
    WHERE       l.id = h.parent
    ),
    hier2 (id, parent) AS (
    SELECT      id, parent
    FROM        table
    WHERE       id = @user2
    UNION ALL
    SELECT      id, parent
    FROM        table l, hier1 h
    WHERE       l.id = h.parent
    )
SELECT  TOP 1 hier1.id
FROM    hier1, hier2
WHERE   hier1.id = hier2.id

Answer 2

WITH
    hier1 (id, parent) AS (
    SELECT  id, parent
    FROM    table l
    WHERE   id = @user1
    UNION ALL
    SELECT  id, parent
    FROM    table l, hier1 h
    WHERE   l.id = parent
    ),
    hier2 (id, parent) AS (
    SELECT  id, parent
    FROM    table l
    WHERE   id = @user2
    UNION ALL
    SELECT  id, parent
    FROM    table l, hier1 h
    WHERE   l.id = parent
    ),
SELECT  TOP 1 hier1.id
FROM    hier1, hier2
WHERE   hier1.id = hier2.id

如何在递归表中获得最低的2行公共父级（SQL）

2 个答案: