在数据库Student_145中实现基本表Student、Course、SC的创建操作

CREATE DATABASE Student_145;  --创建数据库Student_145
GO
USE Student_145;  --如Student_145已存在，请从本行开始执行。
CREATE TABLE Student                     
    (
    Sno CHAR(5)  PRIMARY KEY,         
    Sname CHAR(20) NOT NULL UNIQUE,            
    Ssex CHAR(2) CONSTRAINT de_Ssex DEFAULT '男', 
    Sage INT CHECK( Sage BETWEEN 16 AND 24), 
    Sdept CHAR(15) CHECK(Sdept IN ('计算机','金融与数学','生物工程') )
    );
CREATE TABLE Course
   (
    Cno CHAR(5) PRIMARY KEY,            
    Cname CHAR(20) NOT NULL,           
    Pre_Cno CHAR(5) REFERENCES Course(Cno), 
    Credits INT, 
    ); 
 CREATE TABLE SC              
    ( 
    Sno CHAR(5) REFERENCES Student(Sno),                
    Cno CHAR(5) REFERENCES Course(Cno),                  
    Grade INT CHECK (Grade>=0 AND Grade<=100), 
    CONSTRAINT Sno_Cno  PRIMARY KEY(Sno,Cno)
    ); 
	CREATE TABLE TEACHER
(
TEACHERID INT IDENTITY(08001,1),
TEACHERNAME CHAR(20),
TEACHERAGE TINYINT
);