如何獲取sqlserver 序列下一個值(本文在網絡上找的)
使用SQL創建序列對象:
IF EXISTS(SELECT * FROM sys.sequences WHERE name = N‘TestSeq‘)
DROP SEQUENCE TestSeq;
GO
--創建序列對象
CREATE SEQUENCE TestSeq AS tinyint
START WITH 1
INCREMENT BY 1;
GO
--創建表
CREATE TABLE TEST
(ID tinyint, Name varchar(150))
--產生序列號碼並插入表中
INSERT INTO TEST
(ID,Name)
VALUES
(NEXT VALUE FOR TestSeq, ‘allen‘)
INSERT INTO TEST
(ID,Name)
VALUES
(NEXT VALUE FOR TestSeq, ‘kevin‘)
SELECT * FROM TEST
--產生序列可以重復使用,下面的例子當序列號碼超過255後又重新從0開始。
CREATE SEQUENCE [dbo].[Test1Seq]
AS [tinyint]
START WITH 0
INCREMENT BY 5
CYCLE
SELECT
NEXT VALUE FOR [Test1Seq]
GO 110
--重新將序列初始值變為5
ALTER SEQUENCE dbo.TestSeq
RESTART WITH 5;
SELECT * FROM sys.sequences WHERE name = ‘TestSeq‘
--共享序列,兩個表可以使用同一個序列對象(Identity列是不可以的)
CREATE SEQUENCE dbo.Seq AS INT
START WITH 1
INCREMENT BY 1
CREATE TABLE dbo.Examp1
(
Seq INT NOT NULL,
Name VARCHAR(50) NOT NULL
);
CREATE TABLE dbo.Examp2
(
Seq INT NOT NULL,
Name VARCHAR(50)NOTNULL
);
INSERT INTO dbo.Examp1(Seq,Name) VALUES (NEXT VALUE FOR dbo.Seq, ‘Tom‘);
INSERT INTO dbo.Examp2(Seq,Name) VALUES (NEXT VALUE FOR dbo.Seq, ‘Jerry‘);
SELECT * FROM Examp1
SELECT * FROM Examp2
--可以直接在查詢中使用序列對象(Identity列是不可以的)
CREATE SEQUENCE SeqOrder AS tinyint
START WITH1
INCREMENT BY1
MINVALUE 1
NO MAXVALUE
CYCLE;
GO
SELECT ID, Name,
NEXT VALUE FOR SeqOrder OVER(ORDER BY Name DESC) As [Order]
FROM test;
為了提升性能,還可以使用CACHE選項,這樣就可以將序列號碼緩存到內存,減少IO操作,值得一提的是序列對象可以指定最大值和最小值,增加值可以為負數。
如何獲取sqlserver 序列下一個值(本文在網絡上找的)