logical database design

Label:In order to build a database with small redundancy and reasonable structure, we must follow certain rules when designing database. In a relational database, this rule is called a paradigm. A paradigm is a summary of a design requirement. In order to design a relational

1. Avoid empty columns in the table; 2. duplicate values or columns should not exist in the table; III:The record in the table should have a unique identifier.When designing a database table, the database administrator should develop a good habit of using an idnumber.It uniquely identifies a row record, rather than distinguishing records by names, numbers, and other fields. Each table should have an ID colu

scripts and database design documents] In addition, add the following technical issues:Problem: Some netizens reported that the time field was missing when MySql guided Sqlite. After local testing, we found that it was indeed gone. After multi-party verification, we found that the time field exists in mysql and is not available in other databases. Therefore, this is generally not used in cross-

ArticleDirectory 1. What are the problems caused by poor database design? 2. Example scenario 3. Summary 1. What are the problems caused by poor database design? In the conceptual design stage of the database, different

Good habits of database design and use, good habits of Database Design Good habits need to be constantly cultivated and strengthened until they become a habit and then part of their thoughts. Before or after work, I want to read "three character classics" or "Di Zigui" for my little guy whenever I have time. He may not

, in banks, government agencies, companies, schools, supermarkets, pharmacies and other places, there are many database instances. This kind of database design process can generally be decomposed into the following steps: It's important to define goals-not to be laughed off by the obvious, because many projects are caused by developers not knowing what the user

Last release: CYQ. DBImport V1.0 Introduction: CYQ. DBImport reverse engineering and batch import database tool V1.0 This release of V2.0 is intended for overseas attacks. The following is a description of this release. I. Introduction to new features of Version 2.0 1: fixed the GUID script error. 2: add processing. When the table for data import has no data, the table structure is also created. The original version needs to be manually created. 3

time-consuming step 2. Conceptual structure Design phase is the key to the entire database design Through the synthesis, induction and abstraction of user requirements, a conceptual model independent of specific DBMS is formed. 3. Logical Structure design phase Convert a co

In fact, I have been preparing the basic materials for another blog post, but I chatted with my friends and asked me what I was doing recently. I said I was working on the System Log Module, after talking with him, this blog came into being. My blog directory: Index writing plan All data can be expressed as follows: ID, table name, column name, and value For example, there is a data entry into the user table: ID (guid, int for ease of understanding) Username Password Email

A simple database design example and a simple database design example An example of database design in a simple management system, including design tables, ergraphs, modeling, and scri

Simple database design and use (FMDB), database design fmdb There is a need: m users share n files, one user may use multiple files, one file may be used by multiple users; if a user leaves, this user will no longer use any files. If a file is not used by any user, the user will delete the file. When a user is known

Typically, there are two ways to judge whether a database is designed to be a comparison specification. One is to see if you have a large number of narrow tables, and the second is whether the number of wide tables is enough. If these two conditions are met, it can be explained that the standard level of the database is still relatively high. This, of course, is a two-a-kind indicator. In order to meet the

relationship is broken down into the standard of 3NF, namely: Each value in the table can only be expressed once. • 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 a

relationship is broken down into the standard of 3NF, namely: Each value in the table can only be expressed once. • 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 a

use a set of design rules for the key. Each table will have an automatic ID as the primary health, the logical master is defined as the first set of candidates, and if the encoding is automatically generated by the database, it is named: ID, and if it is a custom logical encoding, it is named with the "id" method. If

workflow of the application unit and develop the project development plan. (2) Demand analysis: Accurate understanding and analysis of user needs. The tasks required in the requirements analysis phase are: A. Analyze user activity and generate business flowchart. B. Determine the system scope and generate a system correlation diagram. C. Analyze the data involved in user activity and generate a streaming diagram. D. Analyze system data and generate a data dictionary. (3) Conceptual

Everything has a life cycle, of course, the database system is no exception! Database design and ER model This chapter is mainly based on the life cycle of the database system, the design phase of which to explain.Let's take a look at the life cycle of the

1. Database design: The process of planning and structuring the relationships between the data entities in the database and the data entities; a good database design:Save storage space for datato ensure the integrity of the datafacilitate the development of database