MySQL 练习1

一个学生表
分别记录姓名，年龄，性别，班级，语文，数学，英语字段
create table student2(
id int primary key ,
name char(20),
sex char(10),
age int(3),
mobile char(20),
class char(10),
english int(10),
chinese int(10),
math int(10)
)engine=innodb default charset=utf8;
insert into student2 values
(1,'小红','女',23,'13813828824','1719',77,88,98),
(2,'小明','男',23,'13713713711','1720',56,66,55),
(3,'小李','男',23,'15915913911','1719',78,64,87),
(4,'小张','男',23,'15915913912','1720',77,76,77),
(5,'小白','女',24,'15915913913','1719',90,89,98),
(6,'小陈','女',19,'15915913914','1719',84,100,81),
(7,'小钱','女',20,'15915913915',null,45,99,93);

题目

题目1
查询1719班学生的成绩信息
SELECT english,chinese,math from student where class=1719 ;
题目2
查询1719班学生语文成绩大于80小于90的学生信息
题目3
查询学生表中5-7行的数据信息
题目4
显示1719班英语成绩为90，数学成绩为98的name与mobile信息
题目5
显示1719班学生信息并且以语文成绩降序排序
题目6
查询1719与1720班，语文成绩与数学成绩都小于80的name与mobile信息
题目7
查询英语平均分大于80分的班级，英语平均分
显示：班级和平均分
条件：avg english>80
题目8
按班级查出数学最高分
题目9
查询出每班数学最低分
题目10
查询每班数学总分
题目11
查询每班数学平均分
题目12
查询出每班学生总数
题目13
在表中插入一条小谢的成绩数据
题目14
把英语分数小于60的同学分数改为60分
SELECT * FROM student2

select english,chinese,math from student2 where class=1719;

select * from student2 where class=1719 and chinese>80 and chinese<90;

select * from student2 limit 4,3;

SELECT name, mobile FROM student2 WHERE class ="1719" AND english = 90 AND math = 98;

SELECT * FROM student2 WHERE class = '1719' ORDER BY chinese DESC;

SELECT name, mobile
FROM student2
WHERE class IN ('1719', '1720')
AND chinese < 80
AND math < 80;

SELECT class, AVG(english)
FROM student2
GROUP BY class
HAVING AVG(english) > 80;

SELECT class, MAX(math)
FROM student2
GROUP BY class;

SELECT class, MIN(math)
FROM student2
GROUP BY class;

SELECT class, SUM(math)
FROM student2
GROUP BY class;

SELECT class, AVG(math)
FROM student2
GROUP BY class;

SELECT class, COUNT(*) ——总数
FROM student2
GROUP BY class;

INSERT INTO student2
VALUES (8, '小谢', '男', 22, '15915913916', '1720', 85, 92, 88);
SELECT * FROM student2

UPDATE student2
SET english = 60
WHERE english < 60;
SELECT * FROM student2