发布于 2016-04-12 04:24:32 | 144 次阅读 | 评论: 0 | 来源: 网友投递
这里有新鲜出炉的SQL Server教程,程序狗速度看过来!
SQL Server 数据库
SQL Server 即 Microsoft SQL Server 。
SQL是英文Structured Query Language的缩写,意思为结构化查询语言。SQL语言的主要功能就是同各种数据库建立联系,进行沟通。按照ANSI(美国国家标准协会)的规定,SQL被作为关系型数据库管理系统的标准语言。
CREATE TABLE test_tb
(
TestId int not null identity(1,1) primary key,
Caption nvarchar(100) null
);
GO
CREATE UNIQUE NONCLUSTERED INDEX un_test_tb
ON test_tb(Caption)
GO
INSERT INTO test_tb (Caption)
VALUES (null)
GO
INSERT INTO test_tb (Caption)
VALUES (null)
GO
CREATE FUNCTION [dbo].[fn_CK_test_tb_Caption]()
RETURNS BIT
AS
BEGIN
IF(EXISTS(
SELECT 1
FROM test_tb AS a
WHERE (Caption IS NOT NULL) AND EXISTS
(SELECT 1 AS Expr1
FROM test_tb
WHERE (Caption IS NOT NULL) AND (Caption = a.Caption) AND (a.TestId <> TestId))
))
RETURN 0
RETURN 1
END
GO
ALTER TABLE test_tb
ADD CONSTRAINT CK_test_tb_Caption CHECK (dbo.fn_CK_test_tb_Caption() = 1)
GO
INSERT INTO test_tb (Caption)
VALUES (null)
GO
INSERT INTO test_tb (Caption)
VALUES (null)
GO
SELECT * FROM test_tb
GO
INSERT INTO test_tb (Caption)
VALUES (N'AAA')
GO
INSERT INTO test_tb (Caption)
VALUES (N'BBB')
GO
INSERT INTO test_tb (Caption)
VALUES (N'BBB')
GO
SELECT * FROM test_tb
GO
CREATE UNIQUE NONCLUSTERED INDEX un_test_tb
ON test_tb(Caption)
WHERE Caption is not null
GO