5-9数据库作业_欧锦宏

创建名字为class 的表

Ceeate table class(id int(2),class int（2）,name varchar(10),age int(2),math gloat（4,2），eng(4,2),yuwen(4,2));

添加数据

Insert into class values(1,1832,"aasd",34,76.6,57.77,88.76),(2,1832,"asshold",28,88.86,87.55,98.88),(3,1832,"ppppppp",20,55.65,75.4,67.76),(4,1832,"nbnbnb",19,64.2,46,84),(5,1832,"sksksks",25,75,95,99);

insert into class values(6,1833,"zcccxxx",20,55,76,88),(7,1833,"innhej",26,88,90,68),(8,1833,"yyyyyy",23,79,55,66),(9,1833,"guugugu",19,99,89,69),(10,1833,"gogogo",32,98,88,78);

1、查询1832班的成绩信息

select math,eng,yuwen from class where class=1832;

2，查询1833班，语文成绩大于80小于90的成绩信息

select * from class where class=1833 and yuwen between 80 and 90;

3，查询学生表中5到10行的数据

select * from class where id limit 4,9;

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 class where class=1833 and eng=98 and yuwen=77;

5，查询出1832班成绩并且按语文成绩排序（降序）

select * from class where class=1832 order by yuwen 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 class where yuwen<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 class,name from class where  yuwen=null;

8，求出班上语文成绩不及格的学生姓名

select name from class where yuwen<60;

9，求出每个班的数学平均成绩

select class,avg(math) from class 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 class,sum(yuwen) from class group by class;

11、将语文成绩不及格的学生成绩改为60分

update class set yuwen="60" where yuwen="<60";

12、三科分数都大于70分的人名和年纪

select name,age from class where  math>70 and eng>70 and yuwen>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 class where eng>70 and math>60 or yuwen>60;

14、统计每个班的人数

select class,count(*) from class group by class;

15、求每个班数学成绩大于80的人数

select class,count(math>80) from class where math>80 group by class;

17、给student表增加3个字段（数据类型及长度自定义，建议要合理）

alter table class add(sex int(1)not null ,phone bigint(12)default 1882888888,adress varchar(100));