Oracle创建表管理表

--创建图书表
create table books_lib
(
 book_id number(10) primary key,  --unique&not null
 book_name varchar2(50) not null 
);
alter table books_lib add publisher  varchar2(50) null;
desc books_lib;
--增加check约束
alter table books_lib  add qty number check(qty>0 and qty<100) unique  not null ;
insert into books_lib values (1,'Oracle编程','中国出版公司',1000);
to_date('1998-07-05','yyyy-mm-dd');
--
create table emp_virtual(
   empno varchar2(10) primary key,
   sal number(7,2),
   comm_rct number(7,2),
   comm_sal number(7,2) generated always as (sal*comm_rct) virtual 
);
insert into emp_virtual(empno,sal,comm_rct) values ('BN7369',5000,0.23);
select * from emp_virtual;
update emp set sal=5000 where empno=7369;
delete * from emp_virtual
--修改表列
alter table books_lib modify publisher varchar2(100);
--删除默认值
alter table  books_lib modify publish_date default null;
--删除表列
alter table books_lib drop column publish_date;
--同时删除publisher和qty列，并删除与其相关的多列约束
alter table books_lib drop (publisher,qty) cascade constraint;
--部分删除表列
删除大量的数据，需要执行很长的时间
将drop column替换成set unused  未使用状态
alter table boos_lib set unused(isbn)  cascade constraint;
--删除被标记为unused的列
alter table books_lib drop unused columns;
--重命名表列
alter table books_lib rename column qty to books_qty;
--重命名表
alter table scott.bookslib rename to booksnewlib;
--删除数据表
drop table  books_lib;
--从回收站（闪回恢复区）中恢复表
flashback table books_lib to before drop;
--立即删除，无法恢复
drop table books_lib cascade constraints purge;

--表注释
comment on table student is '学生表'；
comment on column student.sno is '学号（主键）';
--查看表的comment
select  * from  all_tab_comments where table_name=upper('student');
--查看列的comment
select * from  all_col_comments where  table_name=upper('student');


CREATE TABLE STUNDET
(
CONSTRAINT FK_BLUE  FOREIGN KEY(ID) REFRENCES CLASSid(id)
)


外键约束的作用 
       外键是该表是另一个表之间联接的字段 外键必须为另一个表中的主键 外键的用途是确保数据的完整性。它通常包括以下几种： 实体完整性，确保每个实体是唯一的（通过主键来实施） 

1 域完整性，确保属性值只从一套特定可选的集合里选择 
2 关联完整性，确保每个外键或是NULL（如果允许的话）或含有与相关主键值相配的值    

有外键约束的表CRUD操作
  1   增加数据：先插入外表，再插入主表
  2   删除数据：先删除主表再删除外表，
  3   有对应记录的值，不能修改当前列；

create table teacher(
       tno   varchar2(3) not null,
       tname varchar2(9) not null,
       tsex  varchar2(3) not null,
       tbirthday date,
       prof  varchar2(9),
       depart varchar2(15) not null,
       constraint pk_teacher primary key(tno)
);

create table course(
       cno       varchar2(5) not null,
       cname     varchar2(15) not null,
       tno       varchar2(3) not null,
       constraint pk_course primary key(cno)
);
create table student(
       sno   varchar2(3) not null,
       sname varchar2(9) not null,
       ssex  varchar2(3) not null,
       sbirthday date,
       sclass varchar2(5),
       constraint pk_student primary key(sno)
);
comment on column student.sno is '学号（主键）';
create table score(
        sno   varchar2(3) not null,
        cno   varchar2(5) not null,
        degree   number(4,1),
        constraint pk_score primary key(sno,cno)--复合主键
);
comment on column score.sno is '学号（主键）';

alter table score add constraint fk_sno foreign key(sno) references student(sno);
--Student表
insert into student(sno,sname,ssex,sbirthday,sclass) values(108,'曾华','男',to_date('1977-09-01','yyyy-mm-dd'),95033);
--score表（添加外键后要先填Student，course表中数据去满足外键约束）
insert into course(cno,cname,tno) values('3-105','计算机导论',825);


--添加外键
alter table course add constraint fk_tno foreign key(tno) references teacher(tno);
alter table emp add  constraint  fk_deptno foregin key(deptno) references dept(deptno);

已存在数据,如何修改表类型
--修改表名，表列
create table test( name1 varchar2(10), email varchar2(10));
alter table test1  add email varchar2(20)
alter table test1 drop column email
alter table test rename to test1   --修改表名
alter table  test1 rename column name1 to name --修改列名
alter table  test1 modify name varchar2(10);  --修改字段类型
--1 修改原字段名
alter table test1 rename column name  to name1;
--2 增加一个与原字段同名字段
alter table test1  add name varchar2(10);
--3 将原字段的数据增加到新的字段 
update test1 set name=trim(name1);
--4 更新完删除字段
alter table test1  drop column name1;

学生系统建表
--建表
--student表+注释
create table student(
sno varchar2(3) not null,
sname varchar2(9) not null,
ssex varchar2(3) not null,
sbirthday date,
sclass varchar2(5),
constraint pk_student primary key(sno)
);
comment on column student.sno is '学号（主键）';
comment on column student.sname is '学生姓名';
comment on column student.ssex is '学生性别';
comment on column student.sbirthday is '学生出生年月日';
comment on column student.sclass is '学生所在班级';
--course表+注释
create table course(
cno varchar2(5) not null,
cname varchar2(15) not null,
tno varchar2(3) not null,
constraint pk_course primary key(cno)
);
comment on column course.cno is '课程编号（主键）';
comment on column course.cname is '课程名称';
comment on column course.tno is '教工编号（外键）';
--score表+注释
create table score(
sno varchar2(3) not null,
cno varchar2(5) not null,
degree number(4,1),
constraint pk_score primary key(sno,cno)
);
comment on column score.sno is '学号（主键）';
comment on column score.cno is '课程编号（主键）';
comment on column score.degree is '成绩';
--teacher表+注释
create table teacher(
tno varchar2(3) not null,
tname varchar2(9) not null,
tsex varchar2(3) not null,
tbirthday date,
prof varchar2(9),
depart varchar2(15) not null,
constraint pk_teacher primary key(tno)
);
comment on column teacher.tno is '教工编号（主键）';
comment on column teacher.tname is '教工姓名';
comment on column teacher.tsex is '教工性别';
comment on column teacher.tbirthday is '教工出生年月';
comment on column teacher.prof is '职称';
comment on column teacher.depart is '教工所在单位';
--添加外键
alter table course add constraint fk_tno foreign key(tno) references teacher(tno);
alter table score add constraint fk_sno foreign key(sno) references student(sno);
alter table score add constraint fk_cno foreign key(cno) references course(cno);
--添加数据
--Student表
insert into student(sno,sname,ssex,sbirthday,sclass) values(108,'曾华','男',to_date('1977-09-01','yyyy-mm-dd'),95033);
insert into student(sno,sname,ssex,sbirthday,sclass) values(105,'匡明','男',to_date('1975-10-02','yyyy-mm-dd'),95031);
insert into student(sno,sname,ssex,sbirthday,sclass) values(107,'王丽','女',to_date('1976-01-23','yyyy-mm-dd'),95033);
insert into student(sno,sname,ssex,sbirthday,sclass) values(101,'李军','男',to_date('1976-02-20','yyyy-mm-dd'),95033);
insert into student(sno,sname,ssex,sbirthday,sclass) values(109,'王芳','女',to_date('1975-02-10','yyyy-mm-dd'),95031);
insert into student(sno,sname,ssex,sbirthday,sclass) values(103,'陆君','男',to_date('1974-06-03','yyyy-mm-dd'),95031);
insert into student(sno,sname,ssex,sbirthday,sclass) values(104,'周晶晶','女',to_date('1974-06-03','yyyy-mm-dd'),95031);
--teacher表
insert into teacher(tno,tname,tsex,tbirthday,prof,depart) values(804,'李诚','男',to_date('1958/12/02','yyyy-mm-dd'),'副教授','计算机系');
insert into teacher(tno,tname,tsex,tbirthday,prof,depart) values(856,'张旭','男',to_date('1969/03/12','yyyy-mm-dd'),'讲师','电子工程系');
insert into teacher(tno,tname,tsex,tbirthday,prof,depart) values(825,'王萍','女',to_date('1972/05/05','yyyy-mm-dd'),'助教','计算机系');
insert into teacher(tno,tname,tsex,tbirthday,prof,depart) values(831,'刘冰','女',to_date('1977/08/14','yyyy-mm-dd'),'助教','电子工程系');
--course表(添加外键后要先填teacher表中数据去满足外键约束)
insert into course(cno,cname,tno) values('3-105','计算机导论',825);
insert into course(cno,cname,tno) values('3-245','操作系统',804);
insert into course(cno,cname,tno) values('6-166','数字电路',856);
insert into course(cno,cname,tno) values('9-888','高等数学',831);
--score表（添加外键后要先填Student，course表中数据去满足外键约束）
insert into score(sno,cno,degree) values(103,'3-245',86);
insert into score(sno,cno,degree) values(105,'3-245',75);
insert into score(sno,cno,degree) values(109,'3-245',68);
insert into score(sno,cno,degree) values(103,'3-105',92);
insert into score(sno,cno,degree) values(105,'3-105',88);
insert into score(sno,cno,degree) values(109,'3-105',76);
insert into score(sno,cno,degree) values(101,'3-105',64);
insert into score(sno,cno,degree) values(107,'3-105',91);
insert into score(sno,cno,degree) values(108,'3-105',78);
insert into score(sno,cno,degree) values(101,'6-166',85);
insert into score(sno,cno,degree) values(107,'6-166',79);
insert into score(sno,cno,degree) values(108,'6-166',81);


--创建scott方案下的emp表副本并包含所有数据
create table emp_copy as select * from emp;
--创建一个架构而不包含任何表数据
create table emp_copy as select * from emp where 1=0;     
   select * from emp_copy;   
--通过改变select 语句,创建不完全相同的类型
create table emp_copy_others as select empno, 
to_char(hiredate,'yyyy-MM-dd') as hiredate from emp;
   
-- 在约束中使用函数和布尔 
create table invoice_check_others
(
 invoice_name varchar2(20),
 invoice_type int,
 invoice_total number(9,2) default 0,
 constraint invoice_ck CHECK(invoice_total between 1 and 1000),
 constraint check_invoice_type check(invoice_type in(1,2,3,4)),
 constraint check_invoice_name check(invoice_name=upper(invoice_name))--必须大写
)    
   
--查看表中所有的约束
select constraint_name,search_condition,status from user_constraints
where table_name=upper('invoice_check_others');


--Merge语句
create table dept60_bonuses
( 
empno number,bonus_amt number
);
insert into dept60_bonuses values(7369,0);
insert into dept60_bonuses values(7788,2);
insert into dept60_bonuses values(7876,3);
select  empno,sal,ename from emp
select * from dept60_bonuses
--合并两张表,根据不同的语句删除,更新
--合并两张表,根据不同的语句删除,更新
merge into dept60_bonuses b
using ( select empno,sal,deptno from emp where deptno=20) e
on (b.empno=e.empno) 
when matched then
update set b.bonus_amt =e.sal*0.2
where b.bonus_amt=0
delete where (e.sal>2500)
when not matched then
insert (b.empno,b.bonus_amt)
values (e.empno,e.sal*0.1)
where (e.sal<4000);