增删改查(不完全)

Posted 2020-10-11 书中有纸不知何言

 --增加
insert into Student values (‘108‘,‘曾华‘,‘男‘,‘1997-09-01‘,‘95033‘)
insert into Student(class,Sbirthday,ssex,sname,son)values
(‘95033‘,‘1975-10-02‘,‘男‘,‘匡明‘,‘105‘)
--删

 --delete from Student 全部删除
  delete from Student where Ssex = ‘null‘
--改
update Student set Sbirthday=‘1977-09-01‘where Son=‘108‘

--查
select * from  Teacher
select * from  Student where Sname=‘匡明‘
select * from  Student where Sbirthday > ‘1975-01-01‘
--模糊查询
select * from Student where Sname like ‘%王%‘
--排序查询
select * from Student order by class ,Son desc
--去重查询
select distinct class from Student
--分组查询
select class,COUNT(*) from Student group by Class
 
select Decree,AVG(*) from Score group by Decree  问题

--子查询
select * from Student where Class in (‘95033‘,‘95031‘)

select * from Score where Decree between 70 and 90


--别名
select sno as 学号
,Con as 班级
,decree from Score