Sql 需要使用父ID复制数据

我有一个具有父子关系的表，并且希望为同一表中的不同实体复制相同的行，以保持父子关系彼此同步

桌子

Id ParentId EnityId CreatedTime
1  null     'me202' 20/1/2019 12:00:25
2  1        'me202' 20/1/2019 12:02:25
3  2        'me202' 20/1/2019 12:04:25
4  1        'me202' 20/1/2019 12:06:25

我想复制实体“me203”的上述记录，例如：

Id ParentId EnityId CreatedTime

1  null     'me202' 20/1/2019 12:00:25
2  1        'me202' 20/1/2019 12:02:25
3  2        'me202' 20/1/2019 12:04:25
4  1        'me202' 20/1/2019 12:06:25

5  null     'me203' 20/1/2019 12:00:25
6  5        'me203' 20/1/2019 12:02:25
7  6        'me203' 20/1/2019 12:04:25
8  5        'me203' 20/1/2019 12:06:25

我正在使用以下查询：

INSERT INTO abc  (ParentId, EnityId)
Select 
Case 
WHEN ParentId IS NULL THEN ParentId 
ELSE

(Select top 1 id From abc Where 
CreatedTime = (Select CreatedTime From abc Where id = ParentId )
AND id != ParentId  AND EnityId = 'me203')
END 
, 'me203'

From abc Where entityid= 'me202'

上述查询将父项插入为null。

如果id列的类型为int identity1,1:

---

哇，这很难看，但它确实有用

DECLARE @StartID int = 1;

DECLARE @Rows table (ID int, ParentID int, EntityID char(5), CreatedTime datetime2(0), [Level] int);

WITH rCTE AS(
    SELECT YT.ID,
           YT.ParentID,
           YT.EntityID,
           YT.CreatedTime,
           1 AS [Level]
    FROM dbo.YourTable YT
    WHERE YT.ID = @StartID
    UNION ALL
    SELECT YT.ID,
           YT.ParentID,
           YT.EntityID,
           YT.CreatedTime,
           r.[Level] + 1 AS [Level]
    FROM dbo.YourTable YT
         JOIN rCTE r ON YT.ParentID = r.ID)
INSERT INTO @Rows (ID,
                   ParentID,
                   EntityID,
                   CreatedTime,
                   Level)

SELECT r.ID,
       r.ParentID,
       'me203' AS EntityID,
       r.CreatedTime,
       r.[Level]
FROM rCTE r
ORDER BY r.ID;

DECLARE @I int = 1;
DECLARE @IDs table (New int, Old int)

WHILE @I <= (SELECT MAX([Level]) FROM @Rows) BEGIN

    MERGE INTO dbo.YourTable YT USING @Rows R ON [Level] != @i
    WHEN NOT MATCHED THEN
        INSERT (ParentID,EntityID, CreatedTime)
        VALUES (R.ParentID, R.EntityID, R.CreatedTime)
        OUTPUT inserted.ID, R.ID
        INTO @IDs (New,Old);

    UPDATE R
    SET R.ParentID = I.New
    FROM @Rows R
         JOIN @IDs I ON R.ParentID = I.Old
    WHERE R.[Level] = @I + 1

    SET @I = @I + 1;

END

---

您只能通过迭代来实现这一点；插入子级的一个要求是知道父级ID的值。但是，如果其他用户正在对表执行插入操作，则可能会出现并发问题。例如，如果谁否决了这一点，谁就可以解释为什么这一点没有用，那就太好了；当DB Fiddle显示时，这将提供请求的结果。

DECLARE @StartID int = 1;

DECLARE @Rows table (ID int, ParentID int, EntityID char(5), CreatedTime datetime2(0), [Level] int);

WITH rCTE AS(
    SELECT YT.ID,
           YT.ParentID,
           YT.EntityID,
           YT.CreatedTime,
           1 AS [Level]
    FROM dbo.YourTable YT
    WHERE YT.ID = @StartID
    UNION ALL
    SELECT YT.ID,
           YT.ParentID,
           YT.EntityID,
           YT.CreatedTime,
           r.[Level] + 1 AS [Level]
    FROM dbo.YourTable YT
         JOIN rCTE r ON YT.ParentID = r.ID)
INSERT INTO @Rows (ID,
                   ParentID,
                   EntityID,
                   CreatedTime,
                   Level)

SELECT r.ID,
       r.ParentID,
       'me203' AS EntityID,
       r.CreatedTime,
       r.[Level]
FROM rCTE r
ORDER BY r.ID;

DECLARE @I int = 1;
DECLARE @IDs table (New int, Old int)

WHILE @I <= (SELECT MAX([Level]) FROM @Rows) BEGIN

    MERGE INTO dbo.YourTable YT USING @Rows R ON [Level] != @i
    WHEN NOT MATCHED THEN
        INSERT (ParentID,EntityID, CreatedTime)
        VALUES (R.ParentID, R.EntityID, R.CreatedTime)
        OUTPUT inserted.ID, R.ID
        INTO @IDs (New,Old);

    UPDATE R
    SET R.ParentID = I.New
    FROM @Rows R
         JOIN @IDs I ON R.ParentID = I.Old
    WHERE R.[Level] = @I + 1

    SET @I = @I + 1;

END