数据库day3作业

一、在数据库中创建一个表student，用于存储学生信息

CREATE TABLE student(
id INT PRIMARY KEY,
name VARCHAR(20) NOT NULL,
grade FLOAT
);

1、向student表中添加一条新记录

	记录中id字段的值为1，name字段的值为"monkey"，grade字段的值为98.5
    insert into student
    -> values(1,'monkey',98.5);

2、向student表中添加多条新记录

insert into student
values(2,‘bob’,95.5),
(3,‘john’,90.0),
(4,‘smith’,88.5);

3、向student表中添加一条新记录，部分数据插入
	
	insert into student
    -> (id,name)
    -> values
    -> (5,'jone');

4、更新表，grade 大于90的加0.5
update student
set grade=grade+0.5
where grade>90;
5、删除成绩为空的记录
DELETE from student where grade is null;
二、用户权限部分
1、创建一个用户test1使他只能本地登录拥有查询student表的权限。
CREATE USER ‘test1’@‘localhost’ IDENTIFIED BY ‘123456’;
GRANT usage ON . TO sun@localhost;
GRANT select ON ‘dd’.‘student’ TO sun@localhost;

2、查询用户test1的权限。
SHOW GRANTS FOR ‘test1’@‘localhost’ ;
3、删除用户test1.
DROP USER ‘test1’@‘localhost’;