Sql server 使用merge..output获取source.id和target.id之间的映射

非常简单，我有两个表源和目标

declare @Source table (SourceID int identity(1,2), SourceName varchar(50))
declare @Target table (TargetID int identity(2,2), TargetName varchar(50))

insert into @Source values ('Row 1'), ('Row 2')

我想将所有行从

@Source

移动到

@Target

，并了解每个

SourceID

的

TargetID

，因为还有需要复制的表

SourceChild

和

TargetChild

，我需要将新的

TargetID

添加到

TargetChild.TargetID

FK列

有几种解决方案

使用while循环或游标一次向目标插入一行（RBAR），并使用

scope\u identity（）

填充

TargetChild

的FK

将临时列添加到

@Target

并插入

SourceID

。然后，您可以加入该列以获取

TargetChild

中FK的

TargetID

设置标识\u为
@Target
插入OFF

，并自行处理分配新值的操作。您将获得一个范围，然后在

TargetChild.TargetID

中使用该范围

我不太喜欢他们中的任何一个。到目前为止，我使用的是游标

我真正想做的是使用insert语句的

output

子句

insert into @Target(TargetName)
output inserted.TargetID, S.SourceID
select SourceName
from @Source as S

但这是不可能的

The multi-part identifier "S.SourceID" could not be bound.

但合并是可能的

merge @Target as T
using @Source as S
on 0=1
when not matched then
  insert (TargetName) values (SourceName)
output inserted.TargetID, S.SourceID;

结果

TargetID    SourceID
----------- -----------
2           1
4           3

我想知道你是否用过这个？如果您对解决方案有任何想法或发现任何问题？它在简单的场景中工作得很好，但是当查询计划由于复杂的源查询而变得非常复杂时，可能会发生一些丑陋的事情。最糟糕的情况是TargetID/SourceID对实际上不匹配

MSDN对该子句的

from_table_name

进行了说明

列前缀，用于指定DELETE、UPDATE或MERGE语句的FROM子句中包含的表，该语句用于指定要更新或删除的行

出于某种原因，他们不会说“要插入、更新或删除的行”，而只说“要更新或删除的行”

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任何想法都是受欢迎的，对于原始问题的完全不同的解决方案都是非常受欢迎的

在我看来，这是合并和输出的一个很好的用途。我已经在几个场景中使用过，到目前为止还没有遇到任何奇怪的情况。 例如，下面是一个测试设置，它将文件夹和其中的所有文件（标识）克隆到新创建的文件夹（guid）中

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我想在@Nathan的示例中添加另一个示例，因为我发现它有些混乱

我的大部分使用真实的表格，而不是临时表格

我也从这里得到了灵感：

---

这里有一个不使用MERGE的解决方案（如果可能的话，我多次尝试避免使用MERGE）。它依赖于两个具有匹配标识列的内存表（如果需要，可以使用临时表），重要的是，在执行插入时使用ORDER BY，以及两个插入之间匹配的条件。。。第一个保存源ID，第二个保存目标ID

-- Setup...   We have a table that we need to know the old IDs and new IDs after copying.
-- We want to copy all of DocID=1
DECLARE @newDocID int = 99;
DECLARE @tbl table (RuleID int PRIMARY KEY NOT NULL IDENTITY(1, 1), DocID int, Val varchar(100));
INSERT INTO @tbl (DocID, Val) VALUES (1, 'RuleA-2'), (1, 'RuleA-1'), (2, 'RuleB-1'), (2, 'RuleB-2'), (3, 'RuleC-1'), (1, 'RuleA-3')

-- Create a break in IDENTITY values.. just to simulate more realistic data
INSERT INTO @tbl (Val) VALUES ('DeleteMe'), ('DeleteMe');
DELETE FROM @tbl WHERE Val = 'DeleteMe';
INSERT INTO @tbl (DocID, Val) VALUES (6, 'RuleE'), (7, 'RuleF');

SELECT * FROM @tbl t;

-- Declare TWO temp tables each with an IDENTITY - one will hold the RuleID of the items we are copying, other will hold the RuleID that we create
DECLARE @input table (RID int IDENTITY(1, 1), SourceRuleID int NOT NULL, Val varchar(100));
DECLARE @output table (RID int IDENTITY(1,1), TargetRuleID int NOT NULL, Val varchar(100));

-- Capture the IDs of the rows we will be copying by inserting them into the @input table
-- Important - we must specify the sort order - best thing is to use the IDENTITY of the source table (t.RuleID) that we are copying
INSERT INTO @input (SourceRuleID, Val) SELECT t.RuleID, t.Val FROM @tbl t WHERE t.DocID = 1 ORDER BY t.RuleID;

-- Copy the rows, and use the OUTPUT clause to capture the IDs of the inserted rows.
-- Important - we must use the same WHERE and ORDER BY clauses as above
INSERT INTO @tbl (DocID, Val)
OUTPUT Inserted.RuleID, Inserted.Val INTO @output(TargetRuleID, Val)
SELECT @newDocID, t.Val FROM @tbl t 
WHERE t.DocID = 1
ORDER BY t.RuleID;

-- Now @input and @output should have the same # of rows, and the order of both inserts was the same, so the IDENTITY columns (RID) can be matched
-- Use this as the map from old-to-new when you are copying sub-table rows
-- Technically, @input and @output don't even need the 'Val' columns, just RID and RuleID - they were included here to prove that the rules matched
SELECT i.*, o.* FROM @output o
INNER JOIN @input i ON i.RID = o.RID

-- Confirm the matching worked
SELECT * FROM @tbl t

---

他们没有提到“insert”的原因是因为from_table_名称在insert into/output语句中无效，“deleted”前缀也是无效的（因为不能通过insert更改现有数据）。顺便说一句：Adam Machanic关于合并功能的博文太棒了！解决了我的问题。谢谢马丁·史密斯的发帖。希望我能给Adam Machanic文章提供更多有趣的+1替代链接，但要实现复制一行和一组子行的简单任务，这似乎异常复杂。。。光标不是更容易理解吗？

-- Copy the FormSectionInstance
DECLARE @FormSectionInstanceTable TABLE(OldFormSectionInstanceId INT, NewFormSectionInstanceId INT)

;MERGE INTO [dbo].[FormSectionInstance]
USING
(
    SELECT
        fsi.FormSectionInstanceId [OldFormSectionInstanceId]
        , @NewFormHeaderId [NewFormHeaderId]
        , fsi.FormSectionId
        , fsi.IsClone
        , @UserId [NewCreatedByUserId]
        , GETDATE() NewCreatedDate
        , @UserId [NewUpdatedByUserId]
        , GETDATE() NewUpdatedDate
    FROM [dbo].[FormSectionInstance] fsi
    WHERE fsi.[FormHeaderId] = @FormHeaderId 
) tblSource ON 1=0 -- use always false condition
WHEN NOT MATCHED
THEN INSERT
( [FormHeaderId], FormSectionId, IsClone, CreatedByUserId, CreatedDate, UpdatedByUserId, UpdatedDate)
VALUES( [NewFormHeaderId], FormSectionId, IsClone, NewCreatedByUserId, NewCreatedDate, NewUpdatedByUserId, NewUpdatedDate)

OUTPUT tblSource.[OldFormSectionInstanceId], INSERTED.FormSectionInstanceId
INTO @FormSectionInstanceTable(OldFormSectionInstanceId, NewFormSectionInstanceId);


-- Copy the FormDetail
INSERT INTO [dbo].[FormDetail]
    (FormHeaderId, FormFieldId, FormSectionInstanceId, IsOther, Value, CreatedByUserId, CreatedDate, UpdatedByUserId, UpdatedDate)
SELECT
    @NewFormHeaderId, FormFieldId, fsit.NewFormSectionInstanceId, IsOther, Value, @UserId, CreatedDate, @UserId, UpdatedDate
FROM [dbo].[FormDetail] fd
INNER JOIN @FormSectionInstanceTable fsit ON fsit.OldFormSectionInstanceId = fd.FormSectionInstanceId
WHERE [FormHeaderId] = @FormHeaderId

-- Setup...   We have a table that we need to know the old IDs and new IDs after copying.
-- We want to copy all of DocID=1
DECLARE @newDocID int = 99;
DECLARE @tbl table (RuleID int PRIMARY KEY NOT NULL IDENTITY(1, 1), DocID int, Val varchar(100));
INSERT INTO @tbl (DocID, Val) VALUES (1, 'RuleA-2'), (1, 'RuleA-1'), (2, 'RuleB-1'), (2, 'RuleB-2'), (3, 'RuleC-1'), (1, 'RuleA-3')

-- Create a break in IDENTITY values.. just to simulate more realistic data
INSERT INTO @tbl (Val) VALUES ('DeleteMe'), ('DeleteMe');
DELETE FROM @tbl WHERE Val = 'DeleteMe';
INSERT INTO @tbl (DocID, Val) VALUES (6, 'RuleE'), (7, 'RuleF');

SELECT * FROM @tbl t;

-- Declare TWO temp tables each with an IDENTITY - one will hold the RuleID of the items we are copying, other will hold the RuleID that we create
DECLARE @input table (RID int IDENTITY(1, 1), SourceRuleID int NOT NULL, Val varchar(100));
DECLARE @output table (RID int IDENTITY(1,1), TargetRuleID int NOT NULL, Val varchar(100));

-- Capture the IDs of the rows we will be copying by inserting them into the @input table
-- Important - we must specify the sort order - best thing is to use the IDENTITY of the source table (t.RuleID) that we are copying
INSERT INTO @input (SourceRuleID, Val) SELECT t.RuleID, t.Val FROM @tbl t WHERE t.DocID = 1 ORDER BY t.RuleID;

-- Copy the rows, and use the OUTPUT clause to capture the IDs of the inserted rows.
-- Important - we must use the same WHERE and ORDER BY clauses as above
INSERT INTO @tbl (DocID, Val)
OUTPUT Inserted.RuleID, Inserted.Val INTO @output(TargetRuleID, Val)
SELECT @newDocID, t.Val FROM @tbl t 
WHERE t.DocID = 1
ORDER BY t.RuleID;

-- Now @input and @output should have the same # of rows, and the order of both inserts was the same, so the IDENTITY columns (RID) can be matched
-- Use this as the map from old-to-new when you are copying sub-table rows
-- Technically, @input and @output don't even need the 'Val' columns, just RID and RuleID - they were included here to prove that the rules matched
SELECT i.*, o.* FROM @output o
INNER JOIN @input i ON i.RID = o.RID

-- Confirm the matching worked
SELECT * FROM @tbl t