Comparison between project development cycle and database design

Comparison between project development cycle and database design

Project development cycle	Database Design
Requirement Analysis	Analyze the customer's business and data processing needs. 1.Collect information (not afraid of many, but afraid of leakage ); 2.Id object; 3.Identifies the attributes of an object; 4.Identifies the relationship between objects;
outline design	design database E-R figure, confirm that the requirement information is correct and complete; split N: n tables with unreasonable relationships;
detailed design	to E-R the diagram is converted into multiple tables for logic design and review using the three major paradigms.
Code	select a specific database for physical implementation, and write code to implement the front-end application.
Software Testing	Add test data for project testing.
Installation and deployment	Encapsulate databases;

 

Some function dependencies: A non-primary key column depends only on one part of the key combination;

Pass function dependency: ColumnADependency ColumnBWhile ColumnsBDependent primary key column, that is, columnAIndirectly dependent on primary key columns;

 

Three paradigms(1nfKey;2nfAll keys;3nfOnly the key ):

1nf: A primary key exists and the column cannot be split;

2nf: Yes1nf. If no key combination exists2nf; If a primary key is combined, no function dependency is ensured;

3nf: Yes2nf. Remove the dependencies of passing functions;

 

Unique criteria for measuring database performance: Data query speed.

Anti-paradigm:Data StandardizationAnd DatabasePerformanceOfPingBalance.