创建一个student表用于存储学生信息
CREATE TABLE student( id INT PRIMARY KEY, name VARCHAR(20) NOT NULL, grade FLOAT );
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 (id,name,grade) values('1','monkey','98.5');
向student表中添加多条新记录 2,"bob",95.5 3,"john",90.0 4,"smith",88.5
insert into student (id,name,grade) values('2','bob','95.5'),('3','john','90.0'),('4','smith','88.5');
向student表中添加一条新记录，部分数据插入 5,"jone"
insert into student (id,name) values('5','jone');
更新表，grade 大于90的加0.5
update student
set grade = grade + 0.5
where grade > 90;
删除成绩为空的记录
delete from student
where grade is null;
用户权限
创建一个用户test1使他只能本地登录拥有查询student表的权限
reate user test1@'localhost' identified by '123';
grant select on db_system.* to test1@'localhost' ;
查询用户test1的权限
show grants for test1@localhost;
删除用户test1
drop user test1@'localhost';
