TSQL父>子>没有游标的子子复制 [英] TSQL Parent > Child > Sub-Child duplication without cursor

问题描述

我正在创建一个SQL 2008 R2存储过程来复制一行及其所有子级.

I am creating a SQL 2008 R2 stored procedure to duplicate a row and all it's children.

这是一个具有父级，子级和子级子的三层设置 给定父级的ID，我需要创建一个副本.

It's a 3-tiered setup with a Parent, Child and Sub-Child Given the ID of the parent I need to create a duplicate.

我已经使用fast_forward cursor解决了它.

I have solved it using a fast_forward cursor.

我知道我也可以通过循环遍历行来做到这一点，但我不认为这会比此游标方法快.你有什么想法?

I know I can also do it with a while loop through rows but I do not believe that will be faster than this cursor method. What are your thoughts?

有没有更好的方法可以在不使用光标的情况下完成此任务?

我考虑的另一种选择是创建一个临时表，其中包含TBLACStages记录的旧/新PKID.

Another option I considered was creating a temp table holding the old / new PKID's of the TBLACStages records.

TBLACStages可能有1到20条对应的行(并且TBLACUpgrade可能每TBLACStages行有3行)

TBLACStages may have anywhere from 1 to 20 corresponding rows (and TBLACUpgrade will likely have 3 rows per TBLACStages row)

CREATE PROCEDURE [dbo].[spDuplicateACUnit]
@pACUnitID bigint = 0 
AS BEGIN
SET NOCOUNT ON;

DECLARE @NewACUnitID bigint = 0

INSERT INTO TBLACUnits ([col1] ,[col2] ,[...] ,[coln]) SELECT [col1] ,[col2] ,[...] ,[coln] FROM TBLACUnits WHERE ACUnitID = @pACUnitID

SELECT @NewACUnitID = SCOPE_IDENTITY()

DECLARE @ACStageID bigint = 0 
    DECLARE @NewACStageID bigint = 0

DECLARE @ACUnitCursor CURSOR

SET @ACUnitCursor = CURSOR LOCAL FAST_FORWARD FOR SELECT ACStageID FROM TBLACStages WHERE TBLACStages.ACUnitID = @pACUnitID

OPEN @ACUnitCursor

FETCH NEXT FROM @ACUnitCursor INTO @ACStageID

WHILE @@FETCH_STATUS = 0 
BEGIN

INSERT INTO TBLACStages ([ACUnitID] ,[col1] ,[col2] ,[...] ,[coln]) SELECT @NewACUnitID ,[col1] ,[col2] ,[...] ,[coln] FROM TBLACStages WHERE TBLACStages.ACStageID = @ACStageID

SELECT @NewACStageID = SCOPE_IDENTITY()

INSERT INTO TBLACUpgrade ([ACStageID] ,[col1] ,[col2] ,[...] ,[coln]) SELECT @NewACStageID ,[col1] ,[col2] ,[...] ,[coln] FROM TBLACUpgrade WHERE TBLACUpgrade.[ACStageID] = @ACStageID

FETCH NEXT FROM @ACUnitCursor INTO @ACStageID 
END

CLOSE @ACUnitCursor DEALLOCATE @ACUnitCursor

END

GO

推荐答案

这应该给您一个想法:

CREATE TABLE t_parent (id INT NOT NULL PRIMARY KEY IDENTITY, value VARCHAR(100))
CREATE TABLE t_child (id INT NOT NULL PRIMARY KEY IDENTITY, parent INT NOT NULL, value VARCHAR(100))
CREATE TABLE t_grandchild (id INT NOT NULL PRIMARY KEY IDENTITY, child INT NOT NULL, value VARCHAR(100))

INSERT
INTO    t_parent (value)
VALUES  ('Parent 1')

INSERT
INTO    t_parent (value)
VALUES  ('Parent 2')

INSERT
INTO    t_child (parent, value)
VALUES  (1, 'Child 2')

INSERT
INTO    t_child (parent, value)
VALUES  (2, 'Child 2')

INSERT
INTO    t_grandchild (child, value)
VALUES  (1, 'Grandchild 1')

INSERT
INTO    t_grandchild (child, value)
VALUES  (1, 'Grandchild 2')

INSERT
INTO    t_grandchild (child, value)
VALUES  (2, 'Grandchild 3')

DECLARE @parent TABLE (oid INT, nid INT)
DECLARE @child TABLE (oid INT, nid INT)

MERGE
INTO    t_parent
USING   (
        SELECT  id, value
        FROM    t_parent
        ) p
ON      1 = 0
WHEN NOT MATCHED THEN
INSERT  (value)
VALUES  (value)
OUTPUT  p.id, INSERTED.id
INTO    @parent;
SELECT  *
FROM    @parent
MERGE
INTO    t_child
USING   (
        SELECT  c.id, p.nid, c.value
        FROM    @parent p
        JOIN    t_child c
        ON      c.parent = p.oid
        ) c
ON      1 = 0
WHEN NOT MATCHED THEN
INSERT  (parent, value)
VALUES  (nid, value)
OUTPUT  c.id, INSERTED.id
INTO    @child;
SELECT  *
FROM    @child;
INSERT
INTO    t_grandchild (child, value)
SELECT  c.nid, gc.value
FROM    @child c
JOIN    t_grandchild gc
ON      gc.child = c.oid
SELECT  *
FROM    t_grandchild

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