Database design Process

The database is not independent, it is always related to the specific application, for the specific application of the establishment. Therefore, before designing the database, we must make clear the purpose of the application, in the design of the database should always consider the user needs, the database and the specific application is mutually reinforcing relationship.

The design process for a database typically includes the following steps:

Determining the purpose of establishing a database and collecting data;

Establish a conceptual model;

Establish a data model;

Implement and maintain database;

1. Determining the purpose of establishing a database and collecting data

The first phase of the database design process is to determine the purpose of establishing a database and collecting data. In general, we also refer to the purpose of establishing a database as a requirement analysis. The task of requirements analysis is to identify the needs of users by investigating the objects to be processed in detail. And by investigating, gathering, and analyzing information to understand what data is needed to be stored in the database and what data processing functions to accomplish. This process is the starting point of database design, it will directly affect the design of the following stages, and affect the design results are reasonable and practical.

After the purpose has been identified, useful data will need to be collected for the purpose. The most important thing to do before you start collecting data is to investigate the user's actual needs and then analyze and express these requirements. There are many ways to investigate user needs, such as checking records, interviewing, opening investigation, designing questionnaires, asking users to fill in or answer questions. One of the more effective methods is the interview, we can use a number of well-designed questionnaires to communicate directly with users. Through full communication, you can understand how they usually use the database, as well as the current information requirements, and then design to meet the needs of the user field, and based on the design of the field collection data.

2. Building a conceptual model

After determining the purpose of establishing the database and completing the data collection, we enter the second phase of the database design process-building the conceptual model. This phase is the key to the whole database design. At design time, it is generally necessary to draw an E-R diagram that reflects the requirements of each application, including the types of entities, attributes, and contacts. Then optimize the initial e-R diagram to eliminate redundancy and possible contradictions. Conceptual model is an objective reflection of user needs, and does not involve specific computer software and hardware environments. Therefore, at this stage we must focus on how to express the user's need for information, regardless of the specific implementation issues.

3. Building a data Model

After completing the last stage, we get a concept model which is independent of the software and hardware of the specific computer. We can then proceed to build a database model, which is the third phase of the database design process. In this stage, we will transform the E-R diagram obtained in the conceptual model into the concrete data model. Through the previous study, we have learned that the data model is generally divided into hierarchical, network, relational and object-oriented models. At present, the relational data model is commonly used, we usually transform e-R diagram into relational data model, in fact, we want to transform the relation between entity, entity and entity to relational mode.

4. Implementing and Maintaining Databases

The final phase is the implementation and maintenance of the database. After the establishment of the data model, we must name the field, determine the type and width of the field, and use the database management system or database language to create the database structure, input data and running, so the implementation of database is the "final realization" of the database design process. If the database runs very successfully, it indicates that the database design task is basically finished, and the future focus is to maintain the database, including doing backup work, database security and integrity adjustment, improving database performance, etc.

The design of database plays an important role in the development of database application system. Only by designing a reasonable database can the application of the database be provided conveniently. However, the database design process will never really end, because as the user needs and specific application changes and expansion, the structure of the database may also change.

Basic functions of database:

Information browsing and querying;

Modification, addition and deletion of information;

Information statistics, summary and so on.

When designing a database, you should keep the following contents in mind:

Design documents, content operation instructions, instance databases, Help and procedural documents (resources, work logs, etc.).