如何在Microsoft SQL Server中实现序列？

有没有人有一种在SQLServer中实现序列之类的东西的好方法

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有时候你只是不想使用GUID，除了它们很难看之外。也许你想要的序列不是数字？此外，插入一行，然后询问数据库的数字是多少，这似乎太老套了。

大致类似于序列。

您可以使用普通的旧表，并将它们用作序列。这意味着您的插入始终是：

BEGIN TRANSACTION  
SELECT number from plain old table..  
UPDATE plain old table, set the number to be the next number  
INSERT your row  
COMMIT  

但不要这样做。锁会坏的

我从SQL Server开始，对我来说，Oracle的“序列”方案看起来像是一个黑客。我猜你是从另一个方向来的，对你来说，scope_identity（）看起来像一个黑客

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忘掉它。入乡随俗

我完全同意，并在去年的一个项目中这样做了

我刚刚创建了一个表，其中包含序列名称、当前值和增量金额

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然后我创建了两个程序来添加和删除它们。和两个函数来获取下一个键和当前键。

如果您想用顺序键插入数据，但不想再次查询数据库来获取刚刚插入的键，我认为您只有两个选择：

通过返回新插入的键值的存储过程执行插入

在客户端实现序列（以便在插入之前知道新密钥）

如果我在做客户端密钥生成，我喜欢guid。我觉得它们非常漂亮

row["ID"] = Guid.NewGuid();

---

这条线应该放在跑车的引擎盖上。

Oracle实现的序列需要在插入之前调用数据库。 SQL Server实现的标识需要在插入后调用数据库

一个并不比另一个更老练。净效果是一样的——依赖/依赖数据存储来提供唯一的人工键值和（在大多数情况下）对存储的两个调用

我假设您的关系模型基于人工键，在本文中，我将提供以下观察结果：

我们决不应该试图赋予人工钥匙以意义；它们的唯一目的应该是链接相关记录

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与订购数据相关的需求是什么？它可以在视图（表示）中处理，还是必须持久化的数据的真实属性

如果您使用的是SQL Server 2005，您可以选择使用行号

创建一个带有标识符的阶段表

在加载stage表之前，截断并重新设置标识符的种子，使其从1开始

装上你的桌子。现在，每行都有一个从1到N的唯一值

创建一个包含序列号的表。这可以是几行，每个序列一行

从创建的序列表中查找序列号。 通过将阶段表中的行数添加到序列号来更新序列号

通过添加查找到的序列号来更新阶段表标识符。这是一个简单的一步过程。 或

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加载目标表，在ETL中加载时将序列号添加到标识符中。这可以利用批量加载程序并允许进行其他转换。

标识列的另一个问题是，如果有多个表的序列号需要唯一，则标识列不起作用。正如Corey Trager提到的，您自己类型的序列实现可能会出现一些锁定问题

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最直截了当的等效解决方案似乎是创建一个SQL Server表，其中包含一列标识，它取代了单独类型的“序列”对象。例如，如果在Oracle中，一个序列中有两个表，例如Dogs-Cats，那么在SQL Server中，您将创建三个数据库对象，所有表都像Dogs-Cats。您可以在Pets表中插入一行，以获取通常使用NEXTVAL的序列号，然后像从用户处获取实际类型的宠物一样，插入Dogs或Cats表。任何额外的公共列都可以从Dogs/Cats表移动到Pets超类型表中，其结果是1）每个序列号都有一行，2）获取序列号时无法填充的任何列都需要具有默认值，3）需要联接才能获取所有列。

Sql Server 2012已引入，允许您生成与任何表都不关联的顺序数值

创建它们很容易：

CREATE SEQUENCE Schema.SequenceName
AS int
INCREMENT BY 1 ;

插入前使用它们的示例：

DECLARE @NextID int ;
SET @NextID = NEXT VALUE FOR Schema.SequenceName;
-- Some work happens
INSERT Schema.Orders (OrderID, Name, Qty)
  VALUES (@NextID, 'Rim', 2) ;

请参阅我的博客，深入了解如何使用序列：

---

考虑以下代码片段

CREATE TABLE [SEQUENCE](
    [NAME] [varchar](100) NOT NULL,
    [NEXT_AVAILABLE_ID] [int] NOT NULL,
 CONSTRAINT [PK_SEQUENCES] PRIMARY KEY CLUSTERED 
(
    [NAME] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]
GO

CREATE PROCEDURE CLAIM_IDS (@sequenceName varchar(100), @howMany int)
AS
BEGIN
    DECLARE @result int
    update SEQUENCE
        set
            @result = NEXT_AVAILABLE_ID,
            NEXT_AVAILABLE_ID = NEXT_AVAILABLE_ID + @howMany
        where Name = @sequenceName
    Select @result as AVAILABLE_ID
END
GO

---

在SQL Server 2012中，您只需使用

CREATE SEQUENCE

在2005年和2008年，您可以使用公共表表达式获得任意序列号列表

下面是一个示例（请注意，MAXRECURSION选项很重要）：

DECLARE@MinValue INT=1；
声明@MaxValue INT=1000；
使用IndexMaker（IndexNumber）作为
(
挑选
@作为索引编号的最小值
联合所有选择
指数编号+1
从…起
索引生成器
其中IndexNumber<@MaxValue
)
挑选
指数
从…起
索引生成器
订购人
指数
选项
（最大递归0）

我用来解决这个问题的方法是一个表'Sequences'，它存储了我所有的序列和一个'nextval'存储过程

Sql表：

CREATE TABLE Sequences (  
    name VARCHAR(30) NOT NULL,  
    value BIGINT DEFAULT 0 NOT NULL,  
    CONSTRAINT PK_Sequences PRIMARY KEY (name)  
);

使用PK_序列只是为了确保永远不会有同名的序列

Sql存储过程：

IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'nextVal') AND type in (N'P', N'PC')) DROP PROCEDURE nextVal;  
GO  
CREATE PROCEDURE nextval  
    @name VARCHAR(30)  
AS  
    BEGIN  
        DECLARE @value BIGINT  
        BEGIN TRANSACTION  
            UPDATE Sequences  
            SET @value=value=value + 1  
            WHERE name = @name;  
            -- SELECT @value=value FROM Sequences WHERE name=@name  
        COMMIT TRANSACTION  
        SELECT @value AS nextval  
    END;  

插入一些序列：

INSERT INTO Sequences(name, value) VALUES ('SEQ_Workshop', 0);
INSERT INTO Sequences(name, value) VALUES ('SEQ_Participant', 0);
INSERT INTO Sequences(name, value) VALUES ('SEQ_Invoice', 0);  

最后得到序列的下一个值

execute nextval 'SEQ_Participant';

一些c#代码从序列表中获取下一个值

public long getNextVal()
{
    long nextval = -1;
    SqlConnection connection = new SqlConnection("your connection string");
    try
    {
        //Connect and execute the select sql command.
        connection.Open();

        SqlCommand command = new SqlCommand("nextval", connection);
        command.CommandType = CommandType.StoredProcedure;
        command.Parameters.Add("@name", SqlDbType.NVarChar).Value = "SEQ_Participant";
        nextval = Int64.Parse(command.ExecuteScalar().ToString());

        command.Dispose();
    }
    catch (Exception) { }
    finally
    {
        connection.Dispose();
    }
    return nextval;
}

正如正确所说，从SQLServer2012开始，有一个内置功能

原来的问题并不重要

CREATE TABLE [dbo].[SequenceContractNumber]
(
    [ContractNumber] [int] IDENTITY(1,1) NOT NULL,

    CONSTRAINT [PK_SequenceContractNumber] PRIMARY KEY CLUSTERED ([ContractNumber] ASC)
)

CREATE PROCEDURE [dbo].[GetNewContractNumber]
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;
    SET XACT_ABORT ON;

    DECLARE @Result int = 0;

    IF @@TRANCOUNT > 0
    BEGIN
        -- Procedure is called when there is an active transaction.
        -- Create a named savepoint
        -- to be able to roll back only the work done in the procedure.
        SAVE TRANSACTION ProcedureGetNewContractNumber;
    END ELSE BEGIN
        -- Procedure must start its own transaction.
        BEGIN TRANSACTION ProcedureGetNewContractNumber;
    END;

    INSERT INTO dbo.SequenceContractNumber DEFAULT VALUES;

    SET @Result = SCOPE_IDENTITY();

    -- Rollback to a named savepoint or named transaction
    ROLLBACK TRANSACTION ProcedureGetNewContractNumber;

    RETURN @Result;
END

DECLARE @VarContractNumber int;
EXEC @VarContractNumber = dbo.GetNewContractNumber;

CREATE TABLE [dbo].[SequenceS2TransactionNumber]
(
    [S2TransactionNumber] [int] IDENTITY(1,1) NOT NULL,
    [Filler] [int] NULL,
    CONSTRAINT [PK_SequenceS2TransactionNumber] 
    PRIMARY KEY CLUSTERED ([S2TransactionNumber] ASC)
)

-- Description: Returns a list of new unique S2 Transaction numbers of the given size
-- The caller should create a temp table #NewS2TransactionNumbers,
-- which would hold the result
CREATE PROCEDURE [dbo].[GetNewS2TransactionNumbers]
    @ParamCount int -- not NULL
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;
    SET XACT_ABORT ON;

    IF @@TRANCOUNT > 0
    BEGIN
        -- Procedure is called when there is an active transaction.
        -- Create a named savepoint
        -- to be able to roll back only the work done in the procedure.
        SAVE TRANSACTION ProcedureGetNewS2TransactionNos;
    END ELSE BEGIN
        -- Procedure must start its own transaction.
        BEGIN TRANSACTION ProcedureGetNewS2TransactionNos;
    END;

    DECLARE @VarNumberCount int;
    SET @VarNumberCount = 
    (
        SELECT TOP(1) dbo.Numbers.Number
        FROM dbo.Numbers
        ORDER BY dbo.Numbers.Number DESC
    );

    -- table variable is not affected by the ROLLBACK, so use it for temporary storage
    DECLARE @TableTransactionNumbers table
    (
        ID int NOT NULL
    );

    IF @VarNumberCount >= @ParamCount
    BEGIN
        -- the Numbers table is large enough to provide the given number of rows
        INSERT INTO dbo.SequenceS2TransactionNumber
        (Filler)
        OUTPUT inserted.S2TransactionNumber AS ID INTO @TableTransactionNumbers(ID)
        -- save generated unique numbers into a table variable first
        SELECT TOP(@ParamCount) dbo.Numbers.Number
        FROM dbo.Numbers
        OPTION (MAXDOP 1);

    END ELSE BEGIN
        -- the Numbers table is not large enough to provide the given number of rows
        -- expand the Numbers table by cross joining it with itself
        INSERT INTO dbo.SequenceS2TransactionNumber
        (Filler)
        OUTPUT inserted.S2TransactionNumber AS ID INTO @TableTransactionNumbers(ID)
        -- save generated unique numbers into a table variable first
        SELECT TOP(@ParamCount) n1.Number
        FROM dbo.Numbers AS n1 CROSS JOIN dbo.Numbers AS n2
        OPTION (MAXDOP 1);

    END;

    /*
    -- this method can be used if the SequenceS2TransactionNumber
    -- had only one identity column
    MERGE INTO dbo.SequenceS2TransactionNumber
    USING
    (
        SELECT *
        FROM dbo.Numbers
        WHERE dbo.Numbers.Number <= @ParamCount
    ) AS T
    ON 1 = 0
    WHEN NOT MATCHED THEN
    INSERT DEFAULT VALUES
    OUTPUT inserted.S2TransactionNumber
    -- return generated unique numbers directly to the caller
    ;
    */

    -- Rollback to a named savepoint or named transaction
    ROLLBACK TRANSACTION ProcedureGetNewS2TransactionNos;

    IF object_id('tempdb..#NewS2TransactionNumbers') IS NOT NULL
    BEGIN
        INSERT INTO #NewS2TransactionNumbers (ID)
        SELECT TT.ID FROM @TableTransactionNumbers AS TT;
    END

END

-- Generate a batch of new unique transaction numbers
-- and store them in #NewS2TransactionNumbers
DECLARE @VarTransactionCount int;
SET @VarTransactionCount = ...

CREATE TABLE #NewS2TransactionNumbers(ID int NOT NULL);

EXEC dbo.GetNewS2TransactionNumbers @ParamCount = @VarTransactionCount;

-- use the generated numbers...
SELECT ID FROM #NewS2TransactionNumbers AS TT;

INSERT INTO @TableTransactions (ID)
EXEC dbo.GetNewS2TransactionNumbers @ParamCount = @VarTransactionCount;

CREATE SEQUENCE Schema.SequenceName
AS int
INCREMENT BY 1 ;

CREATE SEQUENCE [dbo].[SequenceFile]
AS int
START WITH 1
INCREMENT BY 1 ;

SELECT NEXT VALUE FOR [dbo].[SequenceFile]

--it is used like this:
-- use the sequence in either insert or select:
Insert into MyTable Values (NextVal('MySequence'), 'Foo');

SELECT NextVal('MySequence');

--you can make as many sequences as you want, by name:
SELECT NextVal('Mikes Other Sequence');

--or a blank sequence identifier
SELECT NextVal('');

  CREATE TABLE SequenceHolder(SeqName varchar(40), LastVal int);

GO
CREATE function NextVAL(@SEQname varchar(40))
returns int
as
begin
    declare @lastval int
    declare @barcode int;

    set @lastval = (SELECT max(LastVal) 
                      FROM SequenceHolder
                     WHERE SeqName = @SEQname);

    if @lastval is null set @lastval = 0

    set @barcode = @lastval + 1;

    --=========== USE xp_cmdshell TO INSERT AND COMMINT NOW, IN A SEPERATE TRANSACTION =============================
    DECLARE @sql varchar(4000)
    DECLARE @cmd varchar(4000)
    DECLARE @recorded int;

    SET @sql = 'INSERT INTO SequenceHolder(SeqName, LastVal) VALUES (''' + @SEQname + ''', ' + CAST(@barcode AS nvarchar(50)) + ') '
    SET @cmd = 'SQLCMD -S ' + @@servername +
              ' -d ' + db_name() + ' -Q "' + @sql + '"'
    EXEC master..xp_cmdshell @cmd, 'no_output'

    --===============================================================================================================

    -- once submitted, make sure our value actually stuck in the table
    set @recorded = (SELECT COUNT(*) 
                       FROM SequenceHolder
                      WHERE SeqName = @SEQname
                        AND LastVal = @barcode);

    --TRIGGER AN ERROR 
    IF (@recorded != 1)
        return cast('Barcode was not recorded in SequenceHolder, xp_cmdshell FAILED!! [' + @cmd +']' as int);

    return (@barcode)

end

GO

COMMIT;

--- LOOSEN SECURITY SO THAT xp_cmdshell will run 
---- To allow advanced options to be changed.
EXEC sp_configure 'show advanced options', 1
GO
---- To update the currently configured value for advanced options.
RECONFIGURE
GO
---- To enable the feature.
EXEC sp_configure 'xp_cmdshell', 1
GO
---- To update the currently configured value for this feature.
RECONFIGURE
GO

—-Run SQLServer Management Studio as Administrator,
—- Login as domain user, not sqlserver user.

--MAKE A DATABASE USER THAT HAS LOCAL or domain LOGIN! (not SQL server login)
--insure the account HAS PERMISSION TO ACCESS THE DATABASE IN QUESTION.  (UserMapping tab in User Properties in SQLServer)

—grant the following
GRANT EXECUTE on xp_cmdshell TO [domain\user] 

—- run the following:
EXEC sp_xp_cmdshell_proxy_account 'domain\user', 'pwd'

--alternative to the exec cmd above: 
create credential ##xp_cmdshell_proxy_account## with identity = 'domain\user', secret = 'pwd'


-—IF YOU NEED TO REMOVE THE CREDENTIAL USE THIS
EXEC sp_xp_cmdshell_proxy_account NULL;


-—ways to figure out which user is actually running the xp_cmdshell command.
exec xp_cmdshell 'whoami.exe'  
EXEC xp_cmdshell 'osql -E -Q"select suser_sname()"'
EXEC xp_cmdshell 'osql -E -Q"select * from sys.login_token"'