作为备忘吧.在机房里输入的.
/*CREATE TABLE Student
(Sno CHAR(9) PRIMARY KEY,
Sname CHAR(20) UNIQUE,
Ssex CHAR(2),
Sage SMALLINT,
Sdept CHAR(20)
);*/
/*CREATE TABLE Course
(Cno CHAR(4) PRIMARY KEY,
Cname CHAR(40),
Cpno CHAR(4),
Credit SMALLINT,
FOREIGN KEY (Cpno) REFERENCES Course(Cno)
);*/
/*ALTER TABLE Student ADD S_entrance CHAR;*/
/*ALTER TABLE Student ALTER COLUMN Sage INT;*/
/*ALTER TABLE Course ADD UNIQUE(Cname);*/
/*INSERT
INTO Student (Sno, Sname, Ssex, Sage,Sdept)
VALUES ('200815128', '陈冬', '男', '20', 'IS');*/
/*INSERT
INTO Student (Sno, Sname, Ssex, Sage,Sdept)
VALUES ('200815129', '李芬', '女', '20', 'SR');*/
/*INSERT
INTO Student (Sno, Sname, Ssex, Sage,Sdept)
VALUES ('200815130', '洋洋', '男', '19', 'SR');*/
/*INSERT
INTO Student (Sno, Sname, Ssex, Sage, Sdept)
VALUES ('200815131', '吴建国', '男', '21', 'IS');*/
/*INSERT
INTO Student (Sno, Sname, Ssex, Sage,Sdept)
VALUES ('200815132', '陈浩南', '男', '20', 'SC');*/
/*INSERT
INTO Student (Sno, Sname, Ssex, Sage, Sdept)
VALUES ('200815133', '春冬', '女', '22', 'SC');*/
UPDATE Student
SET S_entrance = '8'
WHERE S_entrance IS NULL;
SELECT *
from Student
通常，你需要获得当前日期和计算一些其他的日期，例如，你的程序可能需要判断一个月的第一天或者最后一天。你们大部分人大概都知道怎样把日期进行分割（年、月、日等），然后仅仅用分割出来的年、月、日等放在几个函数中计算出自己所需要的日期！在这篇文章里，我将告诉你如何� ......
