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sql - CTE 递归选择并插入到具有新 id 和一些更新字段的同一个表中

问题描述

假设我有这张桌子：

|TeamId |Name           |ActiveYear |ParentTeamId |OriginTeamId |
+-------+---------------+-----------+-------------+-------------+
|1      |Founding Team  |2020       |NULL         |NULL         |
|2      |Elders Team    |2020       |1            |NULL         |
|3      |Younger Team   |2020       |1            |NULL         |
|4      |Women Team     |2020       |2            |NULL         |
|5      |Men´s Team     |2020       |2            |NULL         |

当我查询它时，我可以看到层次结构：

WITH abcd AS 
(
    -- anchor
    SELECT 
        CAST((Convert(varchar(20), TeamId)) AS VARCHAR(1000)) AS "Tree",
        TeamId, [Name], Activeyear, ParentTeamId, OriginTeamId
    FROM    
        Teams AS p
    WHERE   
        ParentTeamId IS NULL And ActiveYear = 2020

    UNION ALL

    --recursive member
    SELECT  
        CAST((CONVERT(varchar(20), a.tree) + '/' + CONVERT(varchar(20), c.TeamId)) AS VARCHAR(1000)) AS "Tree",
        c.TeamId, c.[Name], c.Activeyear, c.ParentTeamId, c.OriginTeamId
    FROM
        Teams AS c
    JOIN 
        abcd AS a ON c.ParentTeamId = a.TeamId
    WHERE   
        c.ActiveYear = 2020
) 
SELECT * 
FROM abcd

在此处输入图像描述

现在，我需要更新此表，重新创建相同的结构，但使用新的 ID 和 Activeyear = 2021。

因此，新的父记录仍将是其他新记录的父记录。

我想做一个查询，它允许我“克隆”这些数据并插入一些更新：ActiveYear = 2021, OriginTeamId(OriginTeamId is to identify where that information come from)

我怎样才能做到这一点？

标签： sqlsql-serverrecursioncommon-table-expressionhierarchy

解决方案

一种方法是分两个步骤。插入没有 ID 的行。然后找出id：

insert into teams (name, activeyear, parentid)
    select name, 2021, parentid
    from teams
    where actdiveyear = 2020;

现在通过查找相应的 id 来更新值。窗口函数可以在这里提供帮助：

insert into teams (name, activeyear, ParentTeamId)
    select name, 2021, ParentTeamId
    from teams
    where activeyear = 2020;

with corresponding as (
      select t2020.teamid  as teamid_2020, t2021.teamid as teamid_2021
      from teams t2020 join
           teams t2021
           on t2020.name = t2021.name
      where t2020.activeyear = 2020 and t2021.activeyear = 2021
     )
update t
    set ParentTeamId = c.teamid_2021
    from teams t join
         corresponding c
         on t.ParentTeamId = c.teamid_2020
     where t.activeyear = 2021;

这是一个 db<>fiddle。

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