logical database design

follows the following principles: A real shape is converted into a relational model. An object attribute is a link attribute. The entity code is the link code. Optimize the data model, determine data dependencies, eliminate redundant connections, and determine the relationship patterns that belong to the nth paradigm. Determine whether to merge or break them down. In general, the relationship is divided into 3NF criteria, namely: Each value in the table can be expressed only once. Each row in t

level of privilege :4.1 in combination with the user's "role permission Level" + "corporate Identity" + "department identification" + "employee identification", go to the employee information sheet to find the appropriate employee, as follows: role Permission LevelValue:1. Company leaders: Find Employee Information sheet. Company Identity = = The user. Corporate identity > All Users;2. Department Leaders:Find Employee Information sheet. Companyidentity = = The user. Company logo Employee Inform

Before designing a database1. Test the existing environmentWhen designing a new database, you should not only carefully study the business needs, but also examine the existing system. Most DatabasesProjects are not built from scratch. Normally, there will always be existing systems within the Organization to meet specific needs (there may be no realAutomatically calculated ). Obviously, the existing system is not perfect, otherwise you do not have to

Abstract: The database is the foundation of the system. If you need to change the fields of the database frequently, or even modify the table and table relationship, I believe that no one will be able to cope with it several times! Because of the changes in the database structure, not only the changes in the database

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:Each value in the table can be expressed only once.•? Each row in the table should be uniquely identified (with a unique ke

Label:I. Interface designRegardless of the student, teacher landing interface is unified, according to the user name entered to determine what kind of interface to enter.After the student login interface:Teacher interface: After the teacher login to the course name interface, select the course to get the second picture.Two. Class diagram designThree. Database designCourses: Course number , classes, teacher number, time, teacher, capacity, prerequisite

used with the price, the prices are used cost, the link with the URL, the image with the image, points with point, record log with records, configuration with config, State with status, pattern mode with mode, classification are unified with category, class type unified with type, factory with factory, orders with order, users with user, admin with admin, password Password, comment Notes are used remark, Article article, news, imports with import, export with export, enable enabled, whether it

handled in three situations:, 1: N, and M: N. 7) The link mode 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

, and M: N.7) The link mode 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

http://blog.csdn.net/taijianyu/article/details/5945490One: Nullable columns should be avoided in the table;Two: The table should not have duplicate values or columns;Three: The records in the table should have a unique identifierIn the database table design, the database administrator should develop a good habit, with an ID number to uniquely identify the row rec

), and then the application provides a set of APIs to encapsulate some operations on the database. It can be called by other applications. This method is suitable for sub-modules (sub-users) that frequently need to change permissions) Try to use a database at the initial stage of system design: (logical) Unless

Relationship Type: Mysql, Oracle non-relational: Mongodb, Redis Database Design Reduces data redundancy, avoids data maintenance anomalies, saves storage space, and efficiently accesses Design Steps Requirements Analysis: What the data is, what attributes it has, the characteristics of the data and attributes (storage features), and the lifecycle of the data

handled in three situations:, 1: N, and M: N. 7) The link mode 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

the database, and instructions for generating, modifying, updating or using these data volumes. If the content of these guidelines is lengthy, a list of the names and chapters of the documents to be read is provided.2.5 Support SoftwareBrief introduction of supporting software directly related to this database, such as database management system, storage locator

Design | data | database | Database design Some conceptions of database design (pattern and database design) I've always had an idea. I

business processing tables, in addition to adding the generated AutoNumber IDs (typically used as primary keys), the time CreateDate (creation time) of the record created, the creator of the record Creatby (note here, no ui_ ID (User Information table User_info primary key ui_id), because there are modified people), finally modified the person Lasteditby, the last modification time lasteditdate. (these can be used directly with Chinese characters, without coding, to improve the efficiency of th

5-2 Database DesignBasic steps Steps:1. Requirements Analysis PhaseThe database design must first understand and analyze the user needs accurately. Demand analysis is the foundation of the entire design process and is the most difficult and time-consuming step.2. Conceptual structure

11 Database Design Guidelines and 11 database guidelines I have followed Author Shivprasad koirala, a former MVC engineer from Microsoft ASP/ASP. NET, is now a CEO in India. If you have any questions about the first translation, please kindly advise. Introduction Before reading this article, I want to tell you that I am not a master of

are linked to the same dimension. Data mart can be considered as a group of dimensions of a single large fact table (or a star schema of one or two fact tables) and its link.8.1.4 database model AdjustmentThe biggest problem with database model adjustment is that the adjustment must be carried out in the design phase and should be done before all development wor

three situations:, 1: n, and m: n. 7) The link mode 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.