beaolivei / database-architecture

Contains notes for database architecture lecture

Go back to how the web works

Naming convention

• postgress and other open source languages: snake_case
• other communities (ex MSSQL - microsoft): PascalCase
• tables names should be plural AND columns names singular

Thinking which tables we need to create

What data does those table need?

Data Types

• look at docs
• most common:
  • integer
  • varchar
  • text
  • boolean
  • date/time

Key types (Primary Key x Foreign Key)

• Primary Key:

  • need to be unique
  • can have any datatype but they are normally numbers (integers)
  • cannot be changed

• Foreign Key

  • used to relate 2 databases
  • need to have the same type as the one from the table you are relating it with

Relationship between tables

• One to one
• One to many
• Many to many

Design Concepts

• Required Fields: make sure you know values that are mandatory to your database. This means security + consistency. Use NOT NULL
• Set a default value: to make sure you cannot get null values that may invalidate your logic
• Have a soft deletion approach: instead of 'dropping database' (which can cause tragic situations), you can add isActive field OR adding the entry to a 'deleted_info' database before moving forward
• Avoid calculated fields: leave it for the front and back end. Avoid possible inconsistencies on you DB
• Avoid arrays as types. If you think you should have an array just create a new table and skip some uncessary complexity

ERDs - Entity Relationship Models

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