【无标题】数据库实验代码

mysql -uroot -pshengri20020423

 create database library;

use library

CREATE TABLE subscribe (
    id INT AUTO_INCREMENT PRIMARY KEY,
    email VARCHAR(255) NOT NULL,
    status TINYINT NOT NULL DEFAULT 0,
    code VARCHAR(10)
);

INSERT INTO subscribe (email, status, code) VALUES
    ('[email protected]', 1, 'abc123'),
    ('[email protected]', 0, 'def456'),
    ('[email protected]', 1, 'ghi789'),
    ('[email protected]', 0, 'jkl012'),
    ('[email protected]', 1, 'mno345');

查看表中数据：

SELECT * FROM subscribe;

SELECT email, status FROM subscribe;

DELETE FROM subscribe WHERE email = '[email protected]';

实验三

 create database StudentInfo

use StudentInfo

CREATE TABLE Student (
    num INT(10) PRIMARY KEY COMMENT '学号',
    name VARCHAR(20) NOT NULL COMMENT '姓名',
    sex VARCHAR(4) NOT NULL COMMENT '性别',
    birthday DATETIME COMMENT '出生日期',
    address VARCHAR(50) COMMENT '家庭住址'
);

 

CREATE TABLE grade (
    id INT(10) PRIMARY KEY COMMENT '编号',
    Course VARCHAR(10) NOT NULL COMMENT '课程名',
    S_num INT(10) NOT NULL COMMENT '学号',
    grade VARCHAR(4) COMMENT '成绩'
);

 

ALTER TABLE grade MODIFY Course VARCHAR(20);

ALTER TABLE grade MODIFY Course varchar(20) AFTER s_num;

ALTER TABLE grade CHANGE grade score VARCHAR(4);

ALTER TABLE grade ENGINE=MyISAM;

RENAME TABLE grade TO gradeInfo;

student

ALTER TABLE student DROP COLUMN address;

ALTER TABLE student ADD phone VARCHAR(15);

DROP TABLE student;

ALTER TABLE table_name
MODIFY column_name new_data_type [constraints];

ALTER TABLE table_name
MODIFY column_name new_data_type [constraints] AFTER column_to_place_after;

创建一个表实验三

create table if not exists user(
    id int primary key auto_increment comment '编号',
    username varchar(20) unique comment '用户名',
    phonenum char(11) not null comment '手机号码',
    gender enum('男','女','保密') comment '性别',
    rtime datetime not null comment '注册时间',
    grade int check (grade >=0 and grade <= 100) comment '会员等级'
);