子女父母关系

Question

将数据从表1复制到表2。我的代码第一次使用，第二次在ParentId中不发送0

我的情况需要这些要点来实现：

1. 父子层次可以达到n级。
2. 父母可以有很多孩子。

3. 表2不应具有表1的ID和父ID数据，但它必须具有自己的ID和父ID，但请记住，两个表之间的父子关系必须匹配。

   -- Table 1
   create table #Table1 (
   Id int, ParentId int, Name varchar(50))
   insert into #Table1 values(6,0, 'person1')
   insert into #Table1 values(7,0, 'person2')
   insert into #Table1 values(8,7, 'person3')
   insert into #Table1 values(9,6, 'person4')
   SELECT * from #Table1
   
   -- Table 2
   create table #Table2 (
   Id int IDENTITY(1,1) PRIMARY KEY, ParentId int, Name varchar(50))
   
   -- below code copy table1 data into table2 on the first try, the second time it does not take correct data.
   SET IDENTITY_INSERT #Table2 ON
   declare @MaxId int;
   select @MaxId=max(id)from #table2; 
   
   ;WITH NewIDs AS (
     SELECT OriginalID=T.Id, ReplacementID=ROW_NUMBER() OVER (ORDER BY T.ID ASC)
     FROM #Table1 AS T
   )
   INSERT INTO #Table2(Id, ParentId, Name)
     SELECT Id=N1.ReplacementID+coalesce(@MaxId, 0),
       ParentId=ISNULL(N2.ReplacementID, 0)+coalesce(@MaxId, 0),
       Name=T.Name
     FROM #Table1 AS T
     INNER JOIN NewIDs AS N1 ON T.Id=N1.OriginalID
     LEFT JOIN NewIDs AS N2 ON T.ParentId=N2.OriginalID
   
   SET IDENTITY_INSERT #Table2 OFF
   
   SELECT * from #Table1
   SELECT * from #Table2
   

**两次执行后，我得到了这个错误的信息（上一个是表1，下一个是table2）**

我期望的结果是

Answer 1

好-我不是100％确信这可以解决您更广泛的业务逻辑问题，但是确实会产生您期望的结果。基本上，当您要创建替换ID时，它必须从表中的最后一个现有ID开始，因此下面将执行此操作。

-- Table 1

create table #Table1 (Id int, ParentId int, Name varchar(50))
insert into #Table1 values(6,0, 'person1')
insert into #Table1 values(7,6, 'person2')
insert into #Table1 values(8,7, 'person3')
insert into #Table1 values(9,7, 'person4')
insert into #Table1 values(10,7, 'person5')
insert into #Table1 values(11,9, 'person6')
insert into #Table1 values(12,11, 'person7')
insert into #Table1 values(13,7, 'person8')

SELECT * from #Table1

-- Table 2
create table #Table2 (Id int IDENTITY(1,1) PRIMARY KEY, ParentId int, Name varchar(50))

-- below code copy table1 data into table2 on first
-- try, the second time it does not work.
SET IDENTITY_INSERT #Table2 ON

declare @MaxId int; -- Change Line 1
select @MaxId = max(id) from #table2; -- Change Line 2

;WITH NewIDs AS
(
  SELECT
    OriginalID = T.Id
    , ReplacementID = ROW_NUMBER() OVER (ORDER BY T.ID ASC)
    , ParentId
  FROM #Table1 AS T
)
INSERT INTO #Table2 (Id, ParentId, [Name])
  SELECT
    N1.ReplacementID + coalesce(@MaxId,0) -- Change Line 3
    , case when T.ParentId = 0 then 0 else ISNULL(N2.ReplacementID, 0) + coalesce(@MaxId,0) end -- Change Line 4
    , T.[Name]
  FROM #Table1 AS T
  INNER JOIN NewIDs AS N1 ON T.Id = N1.OriginalID
  LEFT JOIN NewIDs AS N2 ON T.ParentId = N2.OriginalID

SET IDENTITY_INSERT #Table2 OFF

SELECT * from #Table1
SELECT * from #Table2