视图问题

[xiaohuan8101]

1.“由于视图没有直接相关的物理数据，所以不能被索引”
这句话中‘不能被索引’的意思是什么？
2.什么是对象视图？

[tsj68]

1.请把出错代码贴出,方便大家分析.
2.不知道中文的对象视图是不是英文的 Materialized View.

关注:

[softrookie]

1、就是不能在试图上创建索引
2、对象视图比较复杂，是一种定义的类型，他的一行被当作一个数据类型，我说的不是很清楚，查相关资料吧

[xiaohuan8101]

看关于‘对象视图’资料不明白

[xiaohuan8101]

在查询中使用视图比较慢的原因，是不是因为不能用索引的缘故？

[gaobh]

视图没有表所具有的索引和外部码。

[beckhambobo]

Object View Example
The following example creates object view emp_object_view of employee_type:

CREATE TYPE employee_type AS OBJECT
( empno NUMBER(4),
ename VARCHAR2(20),
job VARCHAR2(9),
mgr NUMBER(4),
hiredate DATE,
sal NUMBER(7,2),
comm NUMBER(7,2) );

CREATE OR REPLACE VIEW emp_object_view OF employee_type
WITH OBJECT IDENTIFIER (empno)
AS SELECT empno, ename, job, mgr, hiredate, sal, comm
FROM emp;

[beckhambobo]

请参考以下各参数
OF type_name

Use this clause to explicitly creates an object view of type type_name. The columns of an object view correspond to the top-level attributes of type type_name. Each row will contain an object instance and each instance will be associated with an object identifier (OID) as specified in the WITH OBJECT IDENTIFIER clause. If you omit schema, Oracle creates the object view in your own schema.

WITH OBJECT IDENTIFIER

The WITH OBJECT IDENTIFIER lets you specify the attributes of the object type that will be used as a key to identify each row in the object view. In most cases these attributes correspond to the primary-key columns of the base table. You must ensure that the attribute list is unique and identifies exactly one row in the view.

If you try to dereference or pin a primary key REF that resolves to more than one instance in the object view, Oracle raises an error.


Note: The 8.0 syntax WITH OBJECT OID is replaced with this syntax for clarity. The keywords WITH OBJECT OID are supported for backward compatibility, but Oracle Corporation recommends that you use the new syntax WITH OBJECT IDENTIFIER.



If the object view is defined on an object table or an object view, you can omit this clause or specify DEFAULT.


DEFAULT
Specify DEFAULT if you want Oracle to use the intrinsic object identifier of the underlying object table or object view to uniquely identify each row.


attribute
Specify an attribute of the object type from which Oracle should create the object identifier for the object view.

[xiaohuan8101]

看的不是很明白
只是大体上了解了一点