3.13数据库作业

八、数据库单表练习题作业：

#创建学生表
CREATE TABLE GRADE(
ID INT PRIMARY KEY AUTO_INCREMENT COMMENT'学号',
NAME VARCHAR(20) COMMENT'姓名',
AGE INT COMMENT'年龄',
CLASS INT COMMENT'班级',
CHINESE INT COMMENT'语文分数',
ENGLISH INT COMMENT'英语分数',
MATH INT COMMENT'数学分数'
)ENGINE=INNODB DEFAULT CHARSET=UTF8 COMMENT'学生表';

#插入表数据
insert into GRADE values
(1,'zhangsan',18,1832,80,90,77),
(2,'lisi',18,1832,90,90,90),
(3,'wangwu',19,1833,99,98,100),
(4,'zhaoliu',17,1833,85,78,85),
(5,'xiaoqi',17,1832,60,80,88),
(6,'xiaoba',18,1833,70,82,90);

1，查询1832班的成绩信息
SELECT chinese, english, math
FROM student
WHERE class = 1832;

2，查询1833班，语文成绩大于80小于90的所有成绩信息
SELECT chinese
FROM student
WHERE class = 1833 and chinese<90 and chinese >80;

3，查询学生表中5到10行的数据
SELECT *
FROM student
WHERE id LIMIT 4,5;

4，显示1832班英语成绩为98，数学成绩为77的姓名与学号,
SELECT id, name
FROM student
WHERE english=98 AND math = 77;

5，查询出1832班成绩并且按语文成绩排序（降序）
SELECT *
FROM student
where class = 1832 ORDER BY chinese DESC;

6，查询1833班与1832班，语文成绩与数学成绩都小于80的姓名。
SELECT NAME
FROM student
where class = 1833 and class = 1832 and chinese < 80 and math < 80;

7，查询出没有参加语文考试的学生姓名和班级名称。
SELECT NAME,class
FROM student
where chinese is null;

8，求出班上语文成绩不及格的学生姓名
SELECT NAME
FROM student
where chinese < 60;

9，求出每个班的数学平均成绩
SELECT AVG(math),class
FROM student
GROUP BY class;

10、求出每个班级语文成绩总分 --涉及到每个的时候都需要分组
SELECT SUM(chinese),class
FROM student
GROUP BY class;

11、将语文成绩不及格的学生语文成绩改为60分
UPDATE student
set chinese = 60
WHERE chinese < 60;

12、三科分数都大于70分的人名和年纪
SELECT name, age
FROM student
WHERE chinese > 70 and english > 70 and math > 70 ;

13、求出英语分数高于70且其它任何一科目大于60分的人和班级
SELECT name, class
FROM student
WHERE english>70 and (chinese > 60 or math >60);

14、统计每个班的人数
SELECT COUNT(class),class
FROM student
GROUP BY class;

15、求每个班数学成绩大于80的人数
SELECT COUNT(class),class
FROM student
WHERE math >80 GROUP BY class;

16、求出每个班英语成绩最高的分数和班级名称 --每个班英语成绩最高
SELECT MAX(english), class
FROM student
GROUP BY class;

17、给GRADE表增加3个字段（数据类型及长度自定义，建议要合理，

ALTER table student add (sex INT(1), sports INT(3), music INT(3));