oracle11g对表的操作

--------------------对表的操作-------------------------- --
创建表 
create table classes (  id number(9) not null primary key,        
classname varchar2(40) not null )     

 --查询表 select * from classes;

--删除表 drop table students;

--修改表的名称 rename alist_table_copy to alist_table;

--显示表结构 describe test --不对没查到

-----------------------对字段的操作----------------------------------- --
增加列 alter table test add address varchar2(40);

--删除列 alter table test drop column address;

--修改列的名称 alter table test modify address addresses varchar(40;

--修改列的属性 alter table test modi

create table test1(        id number(9) primary key not null,      
  name varchar2(34)       ) 
rename test2 to test;

--创建自增的序列 create sequence class_seq increment by 1 start with 1 MAXVALUE 999999 NOCYCLE NOCACHE;

select class_seq.currval from dual

--插入数据 insert into classes values(class_seq.nextval,'软件一班') commit;

--更新数据 update stu_account set username='aaa' where count_id=2; commit;

--创建唯一索引 create unique index username on stu_account(username);   --唯一索引 不能插入相同的数据

--行锁 在新打开的对话中不能对此行进行操作 select * from stu_account t where t.count_id=2 for update; --行锁

--alter table stuinfo modify sty_id to stu_id;

alter table students drop constraint class_fk; 
alter table students add constraint class_fk foreign key (class_id) references classes(id);

--外键约束 alter table stuinfo add constraint stu_fk foreign key (stu_id) references students(id) ON DELETE CASCADE;--外键约束,级联删除

alter table stuinfo drop constant stu_fk;  

insert into students values(stu_seq.nextval,'张三',1,sysdate);

insert into stuinfo values(stu_seq.currval,'威海');

select * from stuinfo;

create table zhuce (zc_id number(9) not null primary key,       
 stu_id number(9) not null, zhucetime date default sysdate)


create table feiyong ( fy_id number(9) not null primary key,        
stu_id number(9) not null, mx_id number(9) not null,       
 yijiao number(7,2) not null default 0,        
qianfei number(7,2) not null        )

create talbe fymingxi(        mx_id number(9) not null primary key,      
  feiyong number(7,2) not null,   
  //共7位数字，小数后有两位        
class_id number(9) not null }

create table card(        card_id number(9) primary key, 
 stu_id number(9) not null,     
 money number(7,2) not null default 0,     
   status number(1) not null default 0   --0表可用,1表挂失 )

--链表查询

select c.classname||'_'||s.stu_name as 班级_姓名,si.address from classes c,students s , stuinfo si 
where c.id=s.class_id and s.id=si.stu_id; insert into students values(stu_seq.nextval,'李四',1,sysdate); 
insert into stuinfo values(stu_seq.currval,'南京');

--函数 select rownum,id,stu_name from students t order by id asc;

 

--中间表实现多对多关联 --（1   1， 1   n，n 1，n n ）

--1 n的描述   1的表不作处理   n的表有1表的字段 --1 1的描述   主外键关联 --n n的描述 中间表实现多对多关联

create　table course(          course_id number(9) not null,
couser_name varchar2(40) not null ) 
alter table course to couse;
create table stu_couse(stu_couse_id number(9) primary key,
stu_id number(9) not null, couse_id number(9) not null)

create unique index stu_couse_unq on stu_couse(stu_id,couse_id); 
--唯一学生 
create sequence stu_couse_seq increment by 1 start with 1 MAXVALUE 999999 NOCYCLE NOCACHE;

create sequence couses_seq increment by 1 start with 1 MAXVALUE 999999 NOCYCLE NOCACHE;
 insert into course values(couses_seq.nextval,'计算机原理'); 
insert into course values(couses_seq.nextval,'编译原理');
 insert into course values(couses_seq.nextval,'数据库原理'); 
insert into course values(couses_seq.nextval,'数据结构');
 insert into course values(couses_seq.nextval,'计算机基础');
 insert into course values(couses_seq.nextval,'C语言初步'); 
commit;

insert into stu_couse values(stu_couse_seq.nextval,1,1);
insert into stu_couse values(stu_couse_seq.nextval,1,3);
insert into stu_couse values(stu_couse_seq.nextval,1,5);
insert into stu_couse values(stu_couse_seq.nextval,1,5);

insert into stu_couse values(stu_couse_seq.nextval,2,1);
commit; 
select * from stu_couse; select * from course;

--select s.stu_name,sc.couse_id, c.couser_name from students s,course c,stu_couse sc where stu_id=1

--select couse_id from stu_couse where stu_id=1

select cl.classname,s.stu_name,c.couser_name from stu_couse sc, students s,course c,classes cl where s.id=sc.stu_id and sc.couse_id=c.course_id and s.class_id=cl.id and s.id=1;

--班级——姓名 
select c.classname,s.stu_name from students s,classes c where s.class_id=c.id and s.id=2;

select * from students s where s.id=2 --班级——姓名——课程

select cl.classname,s.stu_name,c.couse_name from stu_couse sc,students s,classes cl,couse c where sc.stu_id=s.id and sc.couse_id=c.couse_id and s.id=26;

--sql 语句的写法，现写出关联到的表，然后写出要查找的字段，第三 写出关联条件   ，记住在写关联到的表时先写数据多的表，这样有助于提高sql的效率

select c.couser_name,s.stu_name from stu_couse sc,students s,course c where c.course_id=1 and c.course_id=sc.couse_id and sc.stu_id=s.id;

select s.stu_name from students s,stu_couse sc where s.id=sc.stu_id group by s.id,s.stu_name;

select c.classname,count(sc.couse_id) from stu_couse sc,students s,classes c where s.class_id=c.id and s.id=sc.stu_id group by c.classname;

select s.stu_name, count(sc.couse_id) from stu_couse sc,students s,classes cl where s.id=sc.stu_id group by s.id,s.stu_name having count(sc.stu_couse_id)>3; 班级 学生 选课数量 select cl.classname,count(sc.stu_couse_id) from stu_couse sc,students s,classes cl where s.id=sc.stu_id and s.class_id=cl.id group by cl.classname;

--班级 学生 选课数量 
select cl.classname,s.stu_name,count(sc.stu_couse_id) from stu_couse sc,students s,classes cl where s.id=sc.stu_id and s.class_id=cl.id group by s.stu_name;

select cl.classname,s.stu_name,count(sc.stu_couse_id) from stu_couse sc ,students s,classes cl where sc.stu_id=s.id and s.class_id=cl.id group by s.id;

select cl.classname,s.stu_name,count(sc.stu_couse_id) from stu_couse sc,students s,classes cl where sc.stu_id=s.id and s.class_id=cl.id group by s.stu_name; --班级 学生 所选课程id 所选课程名称

--创建试图 目的把表联合起来 然后看成一个表，在与其他的联合进行查询 create view xsxk as select cl.classname, s.stu_name,c.couse_id, c.couse_name from stu_couse sc,students s,classes cl,couse c where sc.stu_id=s.id and sc.couse_id=c.couse_id and s.class_id=cl.id;

select * from xsxk

create view classstu as select s.id,c.classname,s.stu_name from students s,classes c where c.id=s.class_id; drop view classstu; 
--删除视图
 select * from classstu;

create view stu_couse_view as select s.id ,c.couse_name from stu_couse sc,students s,couse c where s.id=sc.stu_id and sc.couse_id=c.couse_id; 
select * from stu_couse_view;

create view csc as select cs.classname,cs.stu_name,scv.couse_name from classstu cs,stu_couse_view scv where cs.id=scv.id;
 select * from csc;

select * from classes cross join students; 
--全连接，相当于select * from classes,students;

select * from classes cl left join students s on cl.id=s.class_id;
 --左连接 不管左表有没有 都显示出来 select * from classes cl right join students s on cl.id=s.class_id; 
--右连接 select * from classes cl full join students s on cl.id=s.class_id; 
--全连接

insert into classes values(class_seq.nextval,'软件四班');

create table sales(        nian varchar2(4),        yeji number(5)        );
 insert into sales values('2001',200); insert into sales values('2002',300); 
insert into sales values('2003',400); insert into sales values('2004',500); 
commit; select * from sales;
 drop table sale;