3。 Logical Database Design 

Logical database design from two perspectives database development。 First, the concept of data model transform into relational database theory based on the criteria that means - between。 Then, as the design of information systems, every computer procedures (including procedures for the input and output format), database support services, statements, and inquiries revealed that a detailed examination。 In this so-called Bottom-up analysis, accurate verification of the need to maintain the database and the data in each affairs, statements and so on the needs of those in the nature of the data。 

For each separate statements, services, and so on the analysis must take into account a specific, limited but complete database view。 When statements, services, and other analysis might be necessary to change the concept of data model。 Especially in large-scale projects, the different analytical systems development staff and the team can work independently in different procedures or in a centralized, the details of their work until all the logic design stage may be displayed。 In these circumstances, logic database design stage must be the original concept of data model and user view these independent or merged into a comprehensive design。 In logic design information systems also identify additional information processing needs of these new demands at this time must be integrated into the logic of earlier identified in the database design。 

Logical database design is based on the final step for the formation of good data specifications and determine the rules, the combination, the data after consultation specifications or converted into basic atomic element。 Most of today's database, these rules from the relational database theory and the process known as standardization。 This step is the result of management of these data have not cited any database management system for a complete description of the database map。 Logical database design completed, we began to identify in detail the logic of the computer program and maintenance, the report contents of the database for inquiries。 

4。 Physical database design and definition 

Physical database design and definition phase decisions computer memory (usually disk) database in the organization, definition of According to the library management system for physical structure, the procedures outlined processing services, produce the desired management information and decision support statements。 The objective of this stage is to design an effective and safe management of all data-processing database, the physical database design to closely integrate the information systems of other physical aspects of the design, including procedures, computer hardware, operating systems and data communications networks。 

5。 Database Implementation 

The database prepared by the realization stage, testing and installation procedures for handling databases。 Designers can use the standard programming language (such as COBOL, C or Visual Basic), the dedicated database processing languages (such as SQL), or the process of the non-exclusive language programming in order to produce a statement of the fixed format, the result will be displayed, and may also include charts。 In achieving stage, but also the completion of all the database files, training users for information systems (database) user setup program。 The final step is to use existing sources of information (documents legacy applications and databases and now needs new data) loading data。 Loading data is often the first step in data from existing files and databases to an intermediate format (such as binary or text files) and then to turn intermediate loading data to a new database。 Finally, running databases and related applications for the actual user maintenance and retrieval of data。 In operation, the regular backup database and the database when damaged or affected resume database。