Database Design Process

Database Design Process

Previously, I paid for the IDC. However, the database just copied the original database step by step and did not follow the steps. This. NET version of the data center charges a lot of fees for us. The database design has become a very important part because it is fully developed according to the steps.

Database technology is the most effective means of information resource management. Database Design refers to constructing the optimal database mode for a given application environment, establishing a database and its application system, and effectively storing data to meet user information requirements and processing requirements.

The steps and stages of database design are as follows:

The database design process consists of six phases:

1. Requirement Analysis

In the demand analysis phase, a comprehensive and detailed investigation should be conducted on the entire application of the system to determine the objectives of the enterprise organization, collect basic data that supports the overall design objectives of the system and requirements for such data, determine user requirements and write these requirements as requirement analysis reports acceptable to both the user and the Database Designer. In this phase, we only need to analyze user activities and generate business flowcharts; determine the scope of the system to generate a general picture; analyze the data involved in user activities, generate data flowcharts; and analyze system data, generate a data dictionary.

2. Conceptual Design

A conceptual model independent of a specific DBMS is formed through the synthesis, induction and abstraction of user requirements, which can be expressed by a E-R diagram.
The conceptual model is used for modeling the information world. The conceptual model does not depend on the data model supported by a DBMS. A conceptual model can be converted to a specific data model supported by a DBMS on a computer.
Concept model features:
(1) Strong semantic expression ability, which can easily and directly express various semantic knowledge in applications.
(2) It should be simple, clear, and easy to understand. It is a language for communication between users and database designers.

3. Logic Design

Converts a conceptual structure to a data model (such as a relational model) supported by a DBMS and optimizes it. To design the logical structure, select the data model that best suits to describe and express the corresponding conceptual structure, and then select the most appropriate DBMS.
To convert a E-R diagram to a relational model is to convert the relationship between the object, the object attributes, and the object into a relational model. This conversion generally follows the following principles:

(1) A real shape is converted into a relational model. An object attribute is a link attribute. The entity code is the link code.
(2) A m: n link is converted into a link mode. The codes of the entities connected to the contact and the attributes of the contact are converted to the Link Attributes. The link code is a combination of Entity Codes.
(3) A 1: n link can be converted into an independent link mode, or merged with the link mode corresponding to n. If it is converted to an independent link mode, the codes of the entities connected to the contact and the attributes of the contact are converted to the link attributes, the link code is the entity code of n.
(4) A link can be converted into an independent link mode, or merged with the link mode corresponding to any end.
(5) One multivariate link between three or more entities is converted into a relational model. The codes and attributes of each object connected to the multivariate link are converted to the link attributes. The link code is a combination of Entity Codes.
(6) links between entities in the same entity set, I .e., self-links, can also be handled in three cases:, 1: n, and m: n.
(7) link modes with the same code can be merged.

 
In order to further improve the performance of the database application system, the data model structure should be modified and adjusted appropriately under the guidance of standardization theory. This is the optimization of the data model. Determine the data dependency. Eliminate redundant connections. Determine which relationship modes belong to the nth paradigm. Determine whether to merge or break them down. In general, the relationship is divided into 3NF criteria, namely:

(1) Each value in a table can be expressed only once.
(2) Each row in the table should be uniquely identified (with a unique key ).
(3) The table should not store non-key information dependent on other keys.

4. Physical Design

Select the physical structure (including the storage structure and access method) that best suits the application environment for the Logical Data Model ). Arranges physical storage and designs indexes based on DBMS features and processing needs to form the internal database mode.

5. implementation stage

Use the Data Language (such as SQL) provided by DBMS and its host language (such as VB..

6. O & M phase

The database application system can be put into operation after trial run. During the operation of the database system, it must be constantly evaluated, adjusted, and modified. Including: Database dumping and recovery, database security, integrity control, database performance monitoring, analysis and improvement, database re-organization and re-construction.