Database Modelling
2016-05-25 14:01:16 0 举报AI智能生成
数据库建模是一种设计数据库结构的过程，它涉及到实体、属性和关系的识别和定义。在这个阶段，数据分析师和数据库设计师使用概念模型、逻辑模型和物理模型来表示数据的结构、关系和存储需求。概念模型是高层次的抽象，用于描述数据的语义和功能；逻辑模型是中间层次的表示，用于描述数据的逻辑结构和关系；物理模型是最底层的表示，用于描述数据的存储方式和性能优化。数据库建模的目标是创建一个高效、可扩展且易于维护的数据库系统，以满足业务需求和数据管理目标。在这个过程中，数据分析师需要考虑数据的完整性、一致性、安全性和可用性，以确保数据库能够满足组织的需求并支持数据分析和决策制定。
作者其他创作
大纲/内容
Relational Database
Conceptual Schema
Internal Schema
External Schema
ADV
Data Independence
Minimize redundancy
Improved consistency
Reduce Program maintenance
Improved data quality
DSV
Developer have to maintain logic among data
Too complex with large amount of tables and relationships
Poor performance for big flow accessing and high concurrency
Development Lifecycle
Planning
Definition
Requirement Analysis
Design
Implementation
Data Loading
Testing
Maintenance
Database Design
Concern
Entities
Information
Relationship
cardinalities
Data Modelling Notation
Entity Relationship Data Model
Data Modelling
Conceptual
ER diagram
A detailed, logical representation of data
EER diagram
Super-type and sub-type
Entities Clustering
Logical
Functional Dependency
Determinant
Key or non key attributes
Candidate Key
Primary Key
Composite Key
Normalization
1st NF
Repeating groups removed
Primary key defined
2nd NF
Partial functional dependencies removed
3rd NF
Transitive dependencies removed
BC NF
Remaining anomalies that result from functional dependencies removed
Why normalization
Derive well-structured relations
Result when the relations are updated or modified
Physical
Goals
Translate logical description of data to technical specifications for storing and retrieving
Provide adequate performance
Ensure data integrity
Security
Recoverablity
Concern
Choosing storage format
Select appropriate file organization
Consider normalized relations
Data volume estimate
Data processing requirements and frequencies
Denormalization
Improve efficiency of input-output operations
File Organizations
Sequential
Indexes
Speed up data retrieval
When to use
For large tables
For columns that are frequently used to retrieve data
When data processing is dominated by data retrieval rather than data maintenance
Hashed
Steps
Transform EER diagrams into relations
Normalize the relations
Merge relations
Database Implementation
Implement the database
Data Definition Language
Data access
Data Manipulation Language
Database administration
Data Control Language
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