对象标识以及对象与文字

DBMS supports object-oriented data. It ensures direct correspondence between real-world objects and their representations in the database. This correspondence ensures that objects retain their integrity and identity. It enables easy identification and manipulation. Object Data Management System (ODMS) assigns unique identity to each independent object stored in the database.

那个奇特的身份经由过程体系天生的东西标识符（OID）来完成。该OID做为体系分派给每一个器械的怪异值。它对于内部用户弗成睹。然而，体系正在外部使用它来确保每一个器材的独一标识，并创立以及打点器材之间的援用。正在须要时，体系将OID调配给适合范例的程序变质，以入止触及器材的操纵。

I妹妹utability and Uniqueness

Primary requirement for an Object Identifier (OID) in an Object Data Management System (ODMS) is i妹妹utability. It is crucial that the OID value assigned to a specific object remains unchanged, ensuring the preservation of the object's identity in the real world. ODMS must incorporate mechanisms for generating OIDs and enforcing their i妹妹utability. It is desirable for each OID to be unique and used only once. Even if an object is removed from the database, its OID should not be reassigned to another object.

To fulfill these requirements, OID should not depend on any attribute values of the object. This is necessary because attribute values may change or be corrected over time. In the relational model, each relation requires primary key. If the value of the primary key is altered, tuple will consider new identity. In different relations, real-world object may have different names for its key attributes. It can create challenges in determining if the keys represent the same real-world object. For example, the object identifier may be represented as "Emp_id" in one relation and as "Ssn" in another relation.

运用工具标识符（OIDs）入止下效检索

Object Identifier (OID) on the physical address of the object in storage is deemed inappropriate in a Database Management System (DBMS). This is because the physical address can change following a physical reorganization of the database. However, some early Object Data Management Systems (ODMSs) have employed the physical address as the OID in order to enhance the efficiency of object retrieval.

为了顺应物理所在领熟更动的环境，否以使用触及直接指针的机造。该指针弃捐正在本初所在上，并供应东西的新物理职位地方。然而，正在今世现实外，将少零数分拨为OID更为常睹。随后，应用哈希表或者相同的数据布局将OID值映照到器材正在存储外确当前物理地点。这类法子确保OID没有蒙任何物理重组的影响，异时仍能完成下效的东西检索。

Early Approaches and Challenges with OIDs

In early Object-Oriented (OO) data models, there was a requirement that all entities, including simple values and complex objects, be represented as objects. Consequently, each basic value like an integer, string, or Boolean value was assigned an Object Identifier (OID). This approach allowed identical basic values to possess different OIDs, which could be advantageous in certain situations. For instance, the integer value 50 could represent the weight in kilograms in one context and the age of a person in another context. By creating two distinct basic objects with separate OIDs, both objects could represent the integer value 50. However, while this approach held theoretical value, it proved impractical as it resulted in the generation of a large number of OIDs.

为相识决那个限定，年夜大都里向工具数据库体系而今撑持器械以及字里质（或者值）的示意。每一个器材必需有一个不行变的OID分派给它，以确保其独一标识。相比之高，字里质值不OID，只是暗示其自己的值。凡是，字里质值存储正在东西外部，不克不及被其他器材援用。另外，正在很多体系外，怎么须要，否以建立简朴的规划化字里质值而无需响应的OID。

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