--view sequence synonyms
view也是可以update的，只要你有update的权限，不过有很多约束
例如：view不能含有 set distinct group by，not null列没有default值，decode等等都不能update delete
create table AAATTT
(
ID CHAR(5) not null,
NAME CHAR(10),
NOTE CHAR(30),
XINGMING VARCHAR2(10),
XINGM VARCHAR2(10),
NUM NUMBER(5,3),
NUM2 NUMBER(4),
NUM3 NUMBER(*,3),
DAT DATE,
TIMLZ TIMESTAMP(6) WITH LOCAL TIME ZONE,
TIMZ TIMESTAMP(6) WITH TIME ZONE
);

create view aaat as select * from aaattt;
--view定义存放在数据字典中如下：
select "ID","NAME","NOTE","XINGMING","XINGM","NUM","NUM2","NUM3","DAT","TIMLZ","TIMZ" from aaattt

insert into aaat(id,name) values ('999','hexiaoling');
commit;

--create or replace view比 drop view再create view更好，不丢失授权和依赖关系

--join view有多个base table，联合视图可更新的条件
1、只能更新主键保留表，如果一个表的primary key也是视图的primary key，那么这个表可以通过视图来更新
2、可以通过instead of trigger来更新base table

--sequence
CREATE SEQUENCE emp_sequence
INCREMENT BY 1
START WITH 1
NOMAXVALUE
NOCYCLE
CACHE 10;
--cache 10,如果遇到instance失败，cache内的数据丢失，sequence则跳过cache内的数值
--可以递增也可以递减，可以循环
NEXTVAL
CURRVAL
DROP SEQUENCE order_seq;

--Synonyms Managing
CREATE PUBLIC SYNONYM public_emp FOR jward.emp
DROP PUBLIC SYNONYM public_emp;
--相关视图
DBA_VIEWS
ALL_VIEWS
USER_VIEWS
DBA_SYNONYMS
ALL_SYNONYMS
USER_SYNONYMS
DBA_SEQUENCES
ALL_SEQUENCES
USER_SEQUENCES
DBA_UPDATABLE_COLUMNS
ALL_UPDATABLE_COLUMNS
USER_UPDATABLE_COLUMNS[@more@]