3月13号作业 周卫杰

#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 GRADE 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 80<chinese<90,chinese,class NAME FROM GRADE WHERE class=1833;
3，查询学生表中5到10行的数据
SELECT * FROM GRADE WHERE id LIMIT 4,6;
4，显示1832班英语成绩为98，数学成绩为77的姓名与学号,
SELECT NAME,ID from GRADE WHERE english=98 OR math=77;
5，查询出1832班成绩并且按语文成绩排序（降序）
SELECT chinese FROM GRADE 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,chinese,math,english FROM GRADE WHERE (class=1833 or 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 GRADE WHERE chinese is null;
8，求出班上语文成绩不及格的学生姓名
SELECT NAME FROM GRADE WHERE chinese<60;
9，求出每个班的数学平均成绩
SELECT AVG(math),class FROM GRADE 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 GRADE GROUP BY class;
11、将语文成绩不及格的学生语文成绩改为60分
UPDATE GRADE 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 GRADE WHERE chinese>70 AND math>70 AND english>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 GRADE WHERE english>70 AND math>60 or chinese>60;
14、统计每个班的人数
sELECT count(*),class FROM GRADE GROUP BY class;
15、求每个班数学成绩大于80的人数
SELECT count(math>80),class FROM GRADE 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 GRADE 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，
insert into GRADE values(7,'xiaozhou',20,1833,70,70,70),
(8,'xiaohu',21,1832,50,50,50),(9,'xiaoming',23,1833,50,80,70);
18、增加字段
ALTER TABLE GRADE add (height FLOAT(3,2),number BIGINT(11),sex VARCHAR(4));
desc GRADE;