Methods and steps of database design ___ Database

A brief introduction of database design Method

Manual test method

Design quality is directly related to the experience and level of the design staff

Lack of scientific theory and engineering method support, the quality of the project is difficult to guarantee

The database runs for a period of time and often discovers various problems to varying degrees, which increases the maintenance cost.

Standard Design Method

Manual Design Side

Basic ideas

Process iterations and progressive refinement

Standard design Method (cont.)

Typical methods:

(1) New Orleans (New Orleans) Method: The database design is divided into four stages

S.b.yao method: Divide the database design into five steps

I.r.palmer method: The database design as a step-by-step process

(2) Computer Aided design

ORACLE Designer 2000

SYBASE PowerDesigner

second, the basic steps of database design

The process of database design (six stages)

1. Requirements Analysis Phase

Accurate understanding and analysis of user requirements (including data and processing)

is the foundation of the whole design process, the most difficult and time-consuming step

2. Conceptual structure Design phase

is the key to the entire database design

Through the synthesis, induction and abstraction of user requirements, a conceptual model independent of specific DBMS is formed.

3. Logical Structure design phase

Convert a conceptual structure to a data model supported by a DBMS

To optimize it

4. Database Physical Design Phase

Select a physical structure (including storage structure and access method) that is best suited to the application environment for the logical data model

5. Database implementation phase

Using the data language, tools and host language provided by DBMS, according to the logical design and physical design results

Establish the database, compile and debug the application, organize the data warehousing, and carry out the trial run

6. Database operation and Maintenance phase

The database application system can be put into operation after trial operation.

It must be evaluated, adjusted and modified continuously in the process of database system operation.

Design features:

In the design process, the design of database and the data processing in the database are closely combined, the requirement analysis, abstraction, design and realization of these two aspects are carried out at the same time in each stage, and each other is referenced and supplemented to perfect the design of two aspects.

Design description at all stages of the design process:

As shown in figure:

　Iii. The process of the formation of database models at all levels

1. Requirements Analysis Phase: Comprehensive application needs of each user

2. Conceptual design phase: Form independent of the machine characteristics, independent of the various DBMS product concept model (e-R diagram)

3. The logic design stage: First, the E-R diagram is converted into the data model of the specific database product support, such as the relational model, the database logic mode is formed, and then according to the user processing requirements and security considerations, the necessary view is established on the base table to form the external model of the data.

4. Physical design phase: according to the characteristics of DBMS and processing needs, physical storage arrangements, indexing, forming a database model