SQL查询语言练习

USE master 
GO 
IF EXISTS (SELECT * FROM sysdatabases WHERE name='MyStudentInfoManage')
DROP DATABASE  MyStudentInfoManage         --删除数据库
GO 
CREATE DATABASE MyStudentInfoManage        --创建数据库
GO 
USE MyStudentInfoManage
GO 

--学生表
IF EXISTS(SELECT * FROM sysobjects WHERE name='Student')
DROP TABLE Student        --删除表
GO 
CREATE TABLE Student
(
   --  Student(S#,Sname,Sage,Ssex) 学生表 
     S# INT NOT NULL PRIMARY KEY ,     --学号
     Sname NVARCHAR(20) NOT NULL,      --姓名
     Sage INT NOT NULL ,               --年龄
     Ssex CHAR(2) NOT NULL             --性别
                       
      
);

--教师表
IF EXISTS(SELECT * FROM sysobjects WHERE name='Teacher')
DROP TABLE Teacher
GO 
CREATE TABLE Teacher
(
  --Teacher(T#,Tname) 教师表
  T# INT NOT NULL PRIMARY KEY,
  Tname NVARCHAR(20) NOT NULL
  
);


--课程表
IF EXISTS(SELECT * FROM sysobjects WHERE name='Course')
DROP TABLE Course
GO 
CREATE TABLE  Course
(
   --Course(C#,Cname,T#) 课程表 
   C# INT NOT NULL PRIMARY KEY ,
   Cname NVARCHAR(20) NOT NULL ,
   T# INT NOT NULL  REFERENCES dbo.Teacher(T#)
  
);

--成绩表
IF EXISTS(SELECT * FROM sysobjects WHERE name='SC')
DROP TABLE SC
GO 
CREATE TABLE SC
(
        --SC(S#,C#,score) 成绩表 
        S# INT NOT NULL REFERENCES dbo.Student(S#),
        C# INT NOT NULL REFERENCES dbo.Course(C#),
        Score INT NOT NULL,
        CONSTRAINT FK_Student_Course PRIMARY  KEY(S#,C#)    --学号和课程号同时座位    
        
);

----------------------------------------------------------------------插入测试数据到数据表(Student)中--------------------------------------------
DELETE FROM dbo.Student;

INSERT INTO dbo.Student
        ( S#, Sname, Sage, Ssex )
VALUES  ( 001, -- S# - int
          N'张三', -- Sname - nvarchar(20)
          20, -- Sage - int
          '男'  -- Ssex - char(2)
          )
          
INSERT INTO dbo.Student
        ( S#, Sname, Sage, Ssex )
VALUES  ( 002, -- S# - int
          N'李四', -- Sname - nvarchar(20)
          21, -- Sage - int
          '男'  -- Ssex - char(2)
          )
 INSERT INTO dbo.Student
        ( S#, Sname, Sage, Ssex )
VALUES  ( 003, -- S# - int
          N'王五', -- Sname - nvarchar(20)
          22, -- Sage - int
          '女'  -- Ssex - char(2)
          ) 
INSERT INTO dbo.Student
        ( S#, Sname, Sage, Ssex )
VALUES  ( 004, -- S# - int
          N'周六', -- Sname - nvarchar(20)
          18, -- Sage - int
          '女'  -- Ssex - char(2)
          )      
          
          
------------------------------------------------------------插入数据到教师表(Teacher)中----------------------------------------------------------
DELETE FROM dbo.Teacher;   
       
INSERT INTO dbo.Teacher
        ( T#, Tname )
VALUES  ( 01, -- T# - int
          N'叶平'  -- Tname - nvarchar(20)
          )      
          
------------------------------------------------------------------插入数据到课程表中-------------------------------------------------------------
DELETE FROM dbo.Course;

INSERT INTO dbo.Course
        ( C#, Cname, T# )
VALUES  ( 001, -- C# - int
          N'语文', -- Cname - nvarchar(20)
          01  -- T# - int
          )    
          
INSERT INTO dbo.Course
        ( C#, Cname, T# )
VALUES  ( 002, -- C# - int
          N'数学', -- Cname - nvarchar(20)
          01  -- T# - int
          )     
          
          
INSERT INTO dbo.Course
        ( C#, Cname, T# )
VALUES  ( 0003, -- C# - int
          N'英语', -- Cname - nvarchar(20)
          01  -- T# - int
          )    
          
          
          
          
--------------------------插入数据到成绩表（SC）中-----------------------------------------------------------------------------------------------
  
DELETE FROM dbo.SC;              
INSERT INTO dbo.SC
        ( S#, C#, Score )
VALUES  ( 001, -- S# - int
          001, -- C# - int
          90  -- Score - int
          )