logical database design

BC paradigm.UsuallyThe conditions of the BC paradigm have multiple equivalents: each non-trivial dependency must have a key code on the left side, and each determinant must contain a key code.The BC paradigm checks both non-primary and primary properties. When only the non-primary attribute is checked, it becomes the third paradigm. The relationship of the BC paradigm must satisfy the third paradigm.It is also possible to say that if a relationship reaches the third paradigm, and it has only on

Tags: Microsoft Difference Detail Related entity HTTP Contact process BSP21. Conceptual Design 1.1 key knowledge of conceptual design 1.2 Discrimination 　　The difference between an entity and an attribute: ① entities can be further described by multiple attributes, but not attributes, which are non-subdivided/segmented atoms. There is a connection between the ② entity or multiple entities, and the attribu

the use of meaningless fields (logical primary key) or meaningful fields (business primary key). Individuals tend to "logical primary key", the reason is that the design of the database model structure clear, the relationship between clear, often more in line with the "third paradigm" (although not intentional, hehe).

description1NF: fields in the database table are single attributes and cannot be divided. This single attribute is composed of basic types, including integer, real number, complex type, logical type, and date type.For example, the following database tables conform to the first paradigm: Field 1 Field 2 Field 3 Field 4

Transfer http://www.wgjz.com/database/other/20070515/89173.html When it comes to databases, I don't think we have to talk about the data structure first. In 1996, when I first went to college to study computer programming, the teacher told us that computer programs = data structures + algorithms. Although the current development of programs has gradually transitioned from process-oriented to object-oriented, I strongly agree with the formula that the

) Design students to select the class and teacher classroom two local e-R diagram. (2) The E-R diagram completed by the above design is merged into a global e-R diagram. (3) Transforming the global e-R diagram into the logical structure of the database represented by the equivalent relational pattern. A :(1) The studen

quickly. This type is more officially called "OLAP".So in other words, if you think inserting, updating, deleting data are more prominent in your program, then design a normalized table or create a flat, denormalized database structure.The following simple chart shows a simple normalized table such as the left Names and Address, how to create a flat table structure by applying an denormalized structure.Rul

. Each row in the table should be uniquely identified (with a unique key). Non-key information that depends on other keys should not be stored in the table. 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. According to the ch

General permission management design (database structure design) and permission management structure designI. Preface The application of the permission management system should be used in three different ways, A. Permission B. Assign permissions. C. Grant Permissions This article only analyzes the application levels of "Use Permission" and "assign permission", an

Design | data | database | Database design Some conceptions of database design (pattern and database design II) ;) Please give us m

Basic steps of database design According to the standard design method, considering the whole process of database and its application system development, the database design is divided into the following 6 stages 1. Demand Analys

Three major paradigms of database design and three major paradigms of Database Design In order to establish a database with low redundancy and reasonable structure, certain rules must be followed when designing the database. In re