第二章上机练习

使用sql语句创建数据库
USE master
GO
IF EXISTS (SELECT * FROM sysdatabases WHERE name = 'MySchool')
  DROP DATABASE MySchool
GO
  
CREATE DATABASE MySchool
 ON 
(
  NAME = ' MySchool_data',                             --主数据文件的逻辑名
  FILENAME = 'D:\project\MySchool_data.mdf' ,  --主数据文件的物理名
  SIZE = 10 MB,  --主数据文件初始大小
  FILEGROWTH = 20 % 
)                                    
 LOG ON  
(
  NAME = 'MySchool_log', 
  FILENAME = 'D:\project\MySchool_log.ldf' ,
  SIZE = 3MB, 
  MAXSIZE = 20MB,
  FILEGROWTH = 1MB
)
GO

使用sql语句创建表subject
USE MySchool
GO
IF EXISTS (SELECT * FROM  sysobjects  WHERE  name='Subject' )
    DROP  TABLE  Subject
GO
CREATE  TABLE Subject    --创建课程表
(
    SubjectNo int  IDENTITY(1,1)  NOT NULL,
    SubjectName nchar(50) NOT NULL,
    ClassHour int NOT NULL,
	GradeId int NOT NULL
) 
GO

使用sql语句创建表result
USE MySchool
GO
IF EXISTS (SELECT * FROM  sysobjects  WHERE  name=' Result' )
    DROP  TABLE Result
GO
CREATE  TABLE Result --创建成绩表
(
    StudentNo int NOT NULL,
	SubjectNo int NOT NULL,
	StudentResult int NOT NULL,
	ExamDate datetime NOT NULL
) 
GO

使用sql语句脚本创建student和grade表
USE MySchool
GO
IF EXISTS(SELECT * FROM  sysobjects  WHERE  name='Student')
  DROP  TABLE  Student
CREATE TABLE [dbo].[Student](
	[StudentNo] [int] NOT NULL,
	[LoginPwd] [nvarchar](50) NOT NULL,
	[StudentName] [nvarchar](50) NOT NULL,
	[Sex] bit NOT NULL,
	[GradeId] [int] NOT NULL,
	[Phone] [nvarchar](50) NULL,
	[Address] [nvarchar](255) NULL,
	[BornDate] [datetime] NOT NULL,
	[Email] [nvarchar](50) NULL,
	[IdentityCard] [varchar](18) NOT NULL
 )

IF EXISTS(SELECT * FROM  sysobjects  WHERE  name='Grade')
  DROP  TABLE  Grade
CREATE TABLE [dbo].[Grade](
	[GradeId] [int] IDENTITY(1,1) NOT NULL,
	[GradeName] [nvarchar](50) NOT NULL
)

添加表约束
USE MySchool
GO
ALTER TABLE Subject   --主键约束（课程编号）
   ADD CONSTRAINT PK_Subject PRIMARY KEY (SubjectNo)

ALTER TABLE Subject  --非空约束（课程名称）
   ADD CONSTRAINT CK_SubjectName CHECK (SubjectName is not null)

ALTER TABLE Subject WITH NOCHECK  --检查约束（学时必须大于等于0）
   ADD CONSTRAINT CK_ClassHour CHECK (ClassHour>=0)

ALTER TABLE Subject   --外键约束（主表Grade和从表Subject建立引用关系）
   ADD CONSTRAINT FK_GradeId          
      FOREIGN KEY (GradeId) REFERENCES Grade (GradeId)
GO

USE MySchool
GO
ALTER TABLE Result   --主键约束（学号、科目号、日期）
   ADD CONSTRAINT PK_Result PRIMARY KEY
      (StudentNo, SubjectNo, ExamDate)

ALTER TABLE Result   --默认约束（日期为系统当前日期）
   ADD CONSTRAINT CK_ExamDate DEFAULT (getdate()) FOR ExamDate

ALTER TABLE Result   --检查约束（分数不能大于100，小于0）
   ADD CONSTRAINT CK_StudentResult CHECK
      (StudentResult BETWEEN 0 AND 100)

ALTER TABLE Result   --外键约束（主表Student和从表Result建立关系）
   ADD CONSTRAINT FK_StudentNo          
      FOREIGN KEY (StudentNo) REFERENCES Student (StudentNo)

ALTER TABLE Result   --外键约束（主表Subject和从表Result建立关系）
   ADD CONSTRAINT FK_SubjectNo          
      FOREIGN KEY (SubjectNo) REFERENCES Subject (SubjectNo)
GO

USE MySchool 
GO
ALTER TABLE Result   -- 删除检查约束
  DROP CONSTRAINT  ck_studentResult

ALTER TABLE Result   -- 修改成绩表中成绩列的数据类型 
  ALTER COLUMN StudentResult DECIMAL (5, 2) 

ALTER TABLE Result   -- 添加检查约束
  ADD Constraint ck_studentResult CHECK
                           (studentresult BETWEEN 0 AND 100)
GO