图丨pexels
作者: Linux超
原文链接:http://cn.hk.uy/xBV
create table student
(
id int primary key auto_increment comment '学号,唯一',
name varchar(255) not null comment '姓名',
age int not null comment '年龄',
class varchar(255) not null comment '班级',
score int not null comment '分数',
address varchar(255) comment '地址'
);
insert into student
(name,age,class,score,address) values
('zhang3','20',3,'99','SZ深圳'),
('li4','19',3,'59','GZ广州'),
('wang2','18',4,'66','SH上海'),
('chexiao','17','1','88','BJ北京');
SELECT max(SCORE) AS '最高分' FROM STUDENT;
SELECT AVG(SCORE) AS '平均分' FROM STUDENT;
SELECT MIN(SCORE) AS '最低分' FROM STUDENT;
SELECT * FROM STUDENT WHERE SCORE > (SELECT AVG(SCORE) FROM STUDENT);
SELECT COUNT(*) AS '总数' FROM STUDENT;
SELECT COUNT(*) FROM STUDENT WHERE CLASS = 3;
SELECT SUM(SCORE) AS '总成绩和' FROM STUDENT;
SELECT UCASE(NAME) AS '姓名' FROM STUDENT;
SELECT LCASE(NAME) AS '小写' FROM STUDENT;
SELECT mid(name,2) FROM STUDENT;
SELECT SUBSTRING(NAME,1,2) FROM STUDENT;
SELECT NAME , LENGTH(NAME) FROM STUDENT;
所有巧合的是要么是上天注定要么是一个人偷偷的在努力。
结束!
作者:BossXiang,可爱且懂得生活的研究生一枚(码农一枚)。
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