Sql 存储过程,为每个调用返回唯一的计算整数
我在我的应用程序中实现了一个事件日志系统来保存代码中的一些事件类型,因此我创建了一个表来存储日志类型和增量ID:Sql 存储过程,为每个调用返回唯一的计算整数,sql,tsql,sql-server-2005,Sql,Tsql,Sql Server 2005,我在我的应用程序中实现了一个事件日志系统来保存代码中的一些事件类型,因此我创建了一个表来存储日志类型和增量ID: |LogType|CurrentId| |info | 1 | |error | 5 | 还有一个表来保存具体的日志记录 |LogType|IdLog|Message | |info |1 |Process started| |error |5 |some error | 因此,每次需要保存新记录时,我都会调用
|LogType|CurrentId|
|info | 1 |
|error | 5 |
还有一个表来保存具体的日志记录
|LogType|IdLog|Message |
|info |1 |Process started|
|error |5 |some error |
因此,每次需要保存新记录时,我都会调用存储过程来计算日志类型的新id,基本上是:newId=(currentId+1)
。但是我在计算时遇到了一个问题,因为如果多个进程同时调用存储过程,“生成的Id”是相同的,因此我得到的日志记录具有相同的Id,并且每个记录的Id必须是唯一的
这是我为SQL Server 2005编写的存储过程:
ALTER PROCEDURE [dbo].[usp_GetLogId]
@LogType VARCHAR(MAX)
AS
BEGIN
SET NOCOUNT ON;
BEGIN TRANSACTION
BEGIN TRY
DECLARE @IdCreated VARCHAR(MAX)
IF EXISTS (SELECT * FROM TBL_ApplicationLogId WHERE LogType = @LogType)
BEGIN
DECLARE @CurrentId BIGINT
SET @CurrentId = (SELECT CurrentId FROM TBL_ApplicationLogId WHERE LogType = @LogType)
DECLARE @NewId BIGINT
SET @NewId = (@CurrentId + 1)
UPDATE TBL_ApplicationLogId
SET CurrentId = @NewId
WHERE LogType = @LogType
SET @IdCreated = CONVERT(VARCHAR, @NewId)
END
ELSE
BEGIN
INSERT INTO TBL_ApplicationLogId VALUES(@LogType, 0)
EXEC @IdCreated = usp_GetLogId @LogType
END
END TRY
BEGIN CATCH
DECLARE @ErrorMessage NVARCHAR(MAX)
SET @ErrorMessage = ERROR_MESSAGE()
IF @@TRANCOUNT > 0
ROLLBACK TRANSACTION;
RAISERROR (@ErrorMessage, 16, 1)
END CATCH
IF @@TRANCOUNT > 0
COMMIT TRANSACTION
SELECT @IdCreated
END
非常感谢您帮助修复存储过程,以便在每次通话中返回唯一的id
它必须在SQL Server 2005上运行。谢谢你能用身份栏实现你想要的吗? 然后,您可以让SQL Server保证唯一性 例如:
create table my_test_table
(
ID int identity
,SOMEVALUE nvarchar(100)
);
insert into my_test_table(somevalue)values('value1');
insert into my_test_table(somevalue)values('value2');
select * from my_test_table
如果出于某种原因,您必须自己发布新的ID值,请尝试使用顺序,如下所示:
if object_id('my_test_table') is not null
begin
drop table my_test_table;
end;
go
create table my_test_table
(
ID int
,SOMEVALUE nvarchar(100)
);
go
if object_id('my_test_sequence') is not null
begin
drop sequence my_test_sequence;
end;
go
CREATE SEQUENCE my_test_sequence
AS INT --other options are here: https://msdn.microsoft.com/en-us/library/ff878091.aspx
START WITH 1
INCREMENT BY 1
MINVALUE 0
NO MAXVALUE;
go
insert into my_test_table(id,somevalue)values(next value for my_test_sequence,'value1');
insert into my_test_table(id,somevalue)values(next value for my_test_sequence,'value2');
insert into my_test_table(id,somevalue)values(next value for my_test_sequence,'value3');
select * from my_test_table
再编辑一次:考虑到需求,我认为这是对现有存储过程的改进。在更新中直接包含新的值计算,最终直接从表返回值(而不是从可能过期的变量返回),并避免递归
下面是完整的测试脚本
if object_id('STACKOVERFLOW_usp_getlogid') is not null
begin
drop procedure STACKOVERFLOW_usp_getlogid;
end
go
if object_id('STACKOVERFLOW_TBL_ApplicationLogId') is not null
begin
drop table STACKOVERFLOW_TBL_ApplicationLogId;
end
go
create table STACKOVERFLOW_TBL_ApplicationLogId(CurrentID int, LogType nvarchar(max));
go
create PROCEDURE [dbo].[STACKOVERFLOW_USP_GETLOGID](@LogType VARCHAR(MAX))
AS
BEGIN
SET NOCOUNT ON;
BEGIN TRANSACTION
BEGIN TRY
DECLARE @IdCreated VARCHAR(MAX)
IF EXISTS (SELECT * FROM STACKOVERFLOW_TBL_ApplicationLogId WHERE LogType = @LogType)
BEGIN
UPDATE STACKOVERFLOW_TBL_APPLICATIONLOGID
SET CurrentId = CurrentID + 1
WHERE LogType = @LogType
END
ELSE
BEGIN
--first time: insert 0.
INSERT INTO STACKOVERFLOW_TBL_ApplicationLogId(CurrentID,LogType) VALUES(0,@LogType);
END
END TRY
BEGIN CATCH
DECLARE @ErrorMessage NVARCHAR(MAX)
SET @ErrorMessage = ERROR_MESSAGE()
IF @@TRANCOUNT > 0
begin
ROLLBACK TRANSACTION;
end
RAISERROR(@ErrorMessage, 16, 1);
END CATCH
select CurrentID from STACKOVERFLOW_TBL_APPLICATIONLOGID where LogType = @LogType;
IF @@TRANCOUNT > 0
begin
COMMIT TRANSACTION
END
end
go
exec STACKOVERFLOW_USP_GETLOGID 'TestLogType1';
exec STACKOVERFLOW_USP_GETLOGID 'TestLogType1';
exec STACKOVERFLOW_USP_GETLOGID 'TestLogType1';
exec STACKOVERFLOW_USP_GETLOGID 'TestLogType2';
exec STACKOVERFLOW_USP_GETLOGID 'TestLogType2';
exec STACKOVERFLOW_USP_GETLOGID 'TestLogType2';
在这里您可以做的不多,但请验证:
- 表TBL_ApplicationLogId按列日志类型编制索引
- @LogType sp参数的数据类型与表TBL_ApplicationLogId中的列LogType相同,因此如果存在索引,它实际上可以使用该索引
- 如果存在并发问题,在选择和更新期间强制表TBL_ApplicationLogId上的锁级别可能会有所帮助。只需在表名后添加(ROWLOCK),例如:TBL_ApplicationLogId(ROWLOCK)
不,约瑟夫。我无法修改此表结构。它必须以这种方式工作。好的,请参阅我编辑的答案版本-您可以从存储过程内部调用序列。这有帮助吗?SEQUENCE语句是在SQL Server 2012中引入的,问题是关于SQL Server 2005的。@JorgeRamírez-那么您将承担技术债务,并且必须承受更复杂、更脆弱、更容易出错的代码。并发环境中唯一性的保证是混乱的,在没有线程相互阻塞的情况下这样做更是混乱。标识列处理所有这些内容。即使您仅为此目的创建一个新表(而不是向TBL_ApplicationLogId表中添加标识列,这似乎是最好的选择),这远比您自己重新创建此控制盘要好。通过在事务外部返回CurrentID(在
提交事务之后
)您进入竞争条件。在提交
和选择
之间,当前被阻止的并发进程可能会开始处理该表,导致两个执行返回相同的值。这不是并发安全的。您可以尝试使用而不是插入触发器生成CurrentId。
ALTER PROCEDURE [dbo].[usp_GetLogId]
@LogType VARCHAR(MAX)
AS
BEGIN
SET NOCOUNT ON;
-- Hold our newly created id in a temp table, so we can use OUTPUT
DECLARE @new_id TABLE (id BIGINT);
-- I think this is thread safe, doing all things in a single statement
----> Check that the log-type has no records
----> If so, then insert an initialising row
----> Output the newly created id into our temp table
INSERT INTO
TBL_ApplicationLogId (
LogType,
CurrentId
)
OUTPUT
INSERTED.CurrentID
INTO
@new_id
SELECT
@LogType, 1
FROM
TBL_ApplicationLogId
WHERE
LogType = @LogType
GROUP BY
LogType
HAVING
COUNT(*) = 0
;
-- I think this is thread safe, doing all things in a single statement
----> Ensure we don't already have a new id created
----> Increment the current id
----> Output it to our temp table
UPDATE
TBL_ApplicationLogId
SET
CurrentId = CurrentId + 1
OUTPUT
INSERTED.CurrentID
INTO
@new_id
WHERE
LogType = @LogType
AND NOT EXISTS (SELECT * FROM @new_id)
;
-- Select the result from our temp table
----> It must be populated either from the INSERT or the UPDATE
SELECT
MAX(id) -- MAX used to tell the system that it's returning a scalar
FROM
@new_id
;
END