请问下 下面的SQL语句到底有什么区别.....
CREATE TABLE stduent (
S_Cod char (10) NOT NULL PRIMARY KEY ,
S_Name char (10) NOT NULL ,
S_Sex char (2) NULL DEFAULT ('男') ,
S_Age tinyint NULL CHECK(S_Age BETWEEN 16 AND 35),
S_Spe char (20) NOT NULL
)
CREATE TABLE [dbo].[stduent] (
[S_Cod] [char] (10) NOT NULL PRIMARY KEY ,
[S_Name] [char] (10) NOT NULL ,
[S_Sex] [char] (2) NULL DEFAULT ('男') ,
[S_Age] [tinyint] NULL CHECK(S_Age BETWEEN 16 AND 35),
[S_Spe] [char] (20) NOT NULL
)
我看了很多SQL语句 中都加上了[] 这个,请问[]有什么用,起的作用是什么,用与不用有什么区别,是用好呢,还是不用好
如果用,是不是什么时候都用呢???
下面的是我在一本教材上看到的代码:
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[t_teaching]') AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[t_teaching](
[t_t_courseno] [char](10) NOT NULL,
[t_t_classno] [char](10) NOT NULL,
[t_t_period] [tinyint] NOT NULL,
[t_t_teacherno] [char](10) NOT NULL,
CONSTRAINT [PK_t_teaching] PRIMARY KEY CLUSTERED
(
[t_t_courseno] ASC,
[t_t_classno] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO