Object-oriented Relational Database Design

 

  

1. Concept Differentiation

 

Some people design Object-Oriented Databases(That is, the database mode) Ideas and Object-Oriented Database Management

Management System(OODBMS. In fact, the former is the idea of Database User-Defined database mode.

The latter is the idea of the database management program. You can use object-oriented methodology to define any

DBMS databases, including network, hierarchical, relational, and object-oriented, and even File System Design

You can also follow the object-oriented approach. Object-oriented thinking or naming rules can be used for System Analysis

System design, program designIt can also be used for data structure design and database design. OOSE from top

Implementation of object-oriented ideas from start to endIs a unity in one breath. Object-oriented Data

The database design is onlyOOSE.

 

Ii. Importance of Database Design

 

Generally, there are two Database Design Methods:That is, property-oriented and entity-oriented. Attribute-oriented

Starting from summarizing the attributes of database applicationsMaintain the function dependency between attributes when merging attribute sets (entities ).

Depends on the relationship. The entity-oriented model starts with looking for entities that are meaningful to database applications.And then

Define attributes to define objects. In general, the number of entities in the real world lies in the number of attributes.When less than 1/10, use the actual

Body-oriented design method. The object-oriented database design is based on the object model., Entity-dominated

Type Design. Generally, database application systems follow the following development steps::

 

1. design the application system structure;

 

2. Select

Application andDBMS Architecture, such as RDBMS;

 

3. Select appropriate DBMS (such as Oracle) and development tools (such as PB) based on the Environment platform used by the application );

 

4. design the database and write SQL programs that define the database mode;

 

5. Write user interface applications that ensure correct data entry into the database;

 

6. Enter database data;

 

7. run various database-related applications to confirm and correct the database content.

 

For the above steps, There are several points to note:

 

(1) This is not a waterfall model. Feedback can be provided at each step.

In the public sector SystemIn addition to feedback, repetition, and parallel processing. For example

Database and table data inputAnd the design of some database tables is still being modified. This is consistent with our incremental development method.

OffIs also related to object-oriented features.

 

(2) The above sequence is not absolute. In most cases, it starts from step 3.

 

(3) For most database application systems, the most important and difficult part of the above steps is not the application system.

The design is a database design.

 

III,DBMS support and database design

 

Why developers of multi-database application systems do not pay attention to Database Design: They are superstitious about DBMS.

To purchase a powerfulThe database design after DBMS is not difficult or important. Some domestic and foreign

Database textbooks are oftenDBMS development vendors do propaganda, but seldom stand in the perspective of database users, from

The database application system introduces the database design method. The results often make readers confused about

It is the design idea of the database management program., Or the idea of using DBMS for database design.

Actually, DBMS only provides a stage for users to use the database, and whether to use this stage

And what to singIt depends entirely on the user's drama script and the arrangement of the Director (developer. Example

For exampleThe database management system used by the public sector system is a metadata table as the basic management unit, supporting all

Relational algebra, full relational database that supports Object Integrity and object referential integrityRDBMS, while we

Use the above on this stage"Item" designs an object-oriented relational database.

 

Iv. Application object model andRDBMS model ing

 

Database Design(Mode) whether to support the object model of the application system. This is to determine whether it is object-oriented.

The basic starting point of the database system. Because the application system is designed beforeThe database design is followed, so the application

The ing from the System Object Model to the database mode is the key to the design of the object-oriented database.

 

　　1. Three-tier database mode extension of the object-oriented model

 

General Database Design Multi-ReferenceA three-layer standard structure proposal for the database model from ANSL/iSCSI.

The internal mode closest to the physical databaseThe SQL statement provided by the DBMS. The concept mode can be composed of several

Internal Mode.It is a set of tables standardized by database users. For example

Division database mode, and locomotive Data Warehouse ModeThey are logical databases, often by database table ID

Define database boundaries. The general concept mode is the boundary of the scope of the physical database mode.It can implement data

Physical Meaning and specificSpecial Operations of DBMS conceal information of external applications. External Mode

Is a database model from the perspective of specific user applicationsFor different applications

To provide a variety of different external modes. For example