Preliminary discussion on database design of "one Card" information system

Design | data | database | Database design
                   Preliminary discussion on database design of             "one Card" information System                                        Fujian Education Equipment Co., Ltd. Chen Youzhang          Introduction: Card application is nothing more than billing and identification of the use. The so-called "one card" is the same card, each user needs only a card, in a variety of different functions of the management of the use. This is the user's basic requirements for the system, but also "one card" the most important performance. A card, not a fixed card, can be an IC card, can also be an ID card, not to specify a manufacturer's card. Card system through flexible interface, unified standards, it is easy to combine various types of cards organically, in the same system, you can use different cards (such as: ID card, Mifare-one card used at the same time). function, a card can be used to stop, open doors, attendance, patrol, identity recognition and so on.     in the "one Card" system database design, the traditional design method is to "one card" system all the data together in the mode of design (that is, "one library card", especially the same business "one card" system products). Although it has the advantages of easy sharing of data, easy data consistency and convenient data retrieval. But also has its fatal shortcoming: first, does not facilitate the system application promotion and the expansion. In fact, "one card" system is a continuous innovation and upgrading of the system, according to market demand and hardware and software related technology development, "one card" system will have new applications to join and the old application of the upgrade. In general, the "one Card" system database needs to make corresponding changes and upgrades, resulting in "card" system data compatibility, consistency, independence and other issues will be very prominent, especiallyis for a relatively long run and relatively large "one card" system (such as: A university City "card" system), the volume of data will be very large, resulting in upgrades and changes in the cost will be very high. Second, the application subsystem can not all be developed by the same company, hardware and software are different, its background database can not be integrated in the "one Card" system database. But they all use the same card as the medium of identification and billing. Therefore, it and the "one Card" system database needs a certain exchange of information (such as: Card opening, loss, hanging, cancellation, supplementary card, etc.). At this time need to increase the corresponding human, equipment, technology and "card" system database related data synchronization. In the absence of relevant standards, the cost is very high.    in fact, "one card" is the use of the same cards as a variety of billing and identification system of the media, this is the "one card" system in common. All kinds of billing and identification systems have their own characteristics and attributes. For example, "one card" system in the catering system and the charging system, one is the amount of food to charge, one is the length of time to charge, it has different characteristics and attributes, in the subsequent database design is also a difference. This is the difference of the "one Card" system. With the above similarities and differences, I think, "one card" information system database design More effective method is "a CADOCU"---to card information database as the Central Library, for each application system or module to establish a dedicated relatively independent database! The advantage of this is to increase the flexibility and independence of the "one card" system to facilitate the expansion and upgrading of the "one Card" application system. But there is another problem: because of the relative independence of each application database, will inevitably lead to card information Database card account opening, loss, hanging, supplementary card, information adjustment, cancellation and other information related to the application system database synchronization problem, this is "one card" information system database design must consider the important issues! In view of the above problems, I think we can take the following measures: 1, in a certain period of time, the application system from the card information database upload or download the relevant information, both sides to carry out the necessary updates! 2, the use of large-scale database server itself distributed replication technology to achieve the synchronization of related information! Both of the above methods should be based on the table structure of each database related table of "one card" system and the related processing mechanism to establish "interface" (i.e. a standard). This standard provides a new topic for database design because it considers the connection between the database and the database, not the entity and entity. I think the following is a more effective scheme: The card information database as the Central Library (card information database records the main information is: _______________________), each application system database set up one or several basic tables with the following information (______________ ____________________）。 As uploading, downloading or implementing distributed replication! This design method is similar to the design method of database logic structure which is related to 1:n. Here the "1" party entity refers to the card information database, the "n" Party entity refers to "one card" each application system or module database. The "foreign keys" Here are the basic tables that are identified above.