数据库创建

创建/删除数据库

create database 数据库名 drop database 数据库名  use数据库

create table 表名() 列名 类型 限制 {

自增Identity(1,1) 非空 Not null

主键  建表时添加  primary key  已经创建好表之后新增约束

alter table 表名  add constraint PK_字段名--"PK"为主键的缩写，字段名为要在其上创建主键的字段名,'PK_字段名'就为约束名，primary key (字段名) --字段名同上

外键 建表时添加  foreign key references 表名（字段）已创建好表之后新增约束alter table 表名 add constraint FK_字段名--"FK"为外键的缩写，foreign key (字段名) references 关联的表名(关联的字段名) --注意'关联的表名'和'关联的字段名'

唯一 unique 

drop table 表名

添加删除列 alert table 表名 add 列名 类型 限制   alter table 表名 drop column 列名

增insert into 表名 values（   ,  ,  ）

删delete from 表名   truncate table 表名：truncate table 表名

改update 表名 set 列名 = 值

}

建立student  score course三个表

create database zuoye
use zuoye
create table student
(
sno varchar(20) not null,
sname varchar(20) not null,
ssex varchar(20) not null,
sbirthday datetime ,
class varchar(20) ,
)
insert into student values('108','曾华','男','1977-09-01','95033')
insert into student values('105','匡明','男','1975-10-02','95031')
insert into student values('107','王丽','女','1976-01-23','95033')
insert into student values('101','李军','男','1976-02-20','95033')
insert into student values('109','王芳','女','1975-02-10','95031')
insert into student values('103','陆君','男','1974-06-03','95031')
select *from student

create table course
(
cno varchar(20) not null,
cname varchar(20) not null,
tno varchar(20) not null,
)
insert into course values('3-105','计算机导论','825')
insert into course values('3-245','操作系统','804')
insert into course values('6-166','数字电路','856')
insert into course values('9-888','高等数学','831')
select *from course

create table score
(
sno varchar(20) not null,
cno varchar(20) not null,
degree decimal(4,1),
)
insert into score values('103','3-245',86)
insert into score values('105','3-245',75)
insert into score values('109','3-245',68)
insert into score values('103','3-105',92)
insert into score values('105','3-105',88)
insert into score values('109','3-105',76)
insert into score values('101','3-105',64)
insert into score values('107','3-105',91)
insert into score values('108','3-105',78)
insert into score values('101','6-166',85)
insert into score values('107','6-166',79)
insert into score values('108','6-166',81)
select *from score

create table teacher
(
tno varchar(20) not null,
tname varchar(20) not null,
tsex varchar(20) not null,
tbirthday datetime ,
prof varchar(20),
depart varchar(20) not null,
)
insert into teacher values('804','李诚','男','1958-12-02','副教授','计算机系')
insert into teacher values('856','张旭','男','1969-03-12','讲师','电子工程系')
insert into teacher values('825','王萍','女','1972-05-05','助教','计算机系')
insert into teacher values('831','刘冰','女','1977-08-14','助教','电子工程系')
select *from teacher