What is data modeling ?

Data Modeling consists in the raw choices of architecture pattern for the database given the business requirement.

A data model is an abstract overview of datas your app needs to store for business needs and how it stores, structures, connects to and organizes it all together (bascially the list of family of datas, types of required values, sources and structures)

The goal is to decompose your App in simple normalized pieces of informations to ensure long term validity and reliability and thus foster scalability, functionality and usability.

Draft a data model step by step

Preparation

• Define main customer use-cases
• Define specific business contents & features for these use-cases

Create the data model

• Entity : identify and define entities - the different kinds of normalized data you need to store to deliver customer goals

  The rule here is that any time a group of values could apply to more than one row on a table, you should consider creating a dedicated entity for these.

• Attributes : define the attributes or fields - the unique variables characteristics of each entity and their type

  • Variants : a concrete subtype of an entity defined by a specific set of attributes
  • Rules : define rules to govern each attributes (format, default values, attributes required, unicity or duplicability of the value)
  • Data source : identity where value will come from (internal db, external db, APIs and web services, flat files, other business assets)

• Relationships : establish the different links and dependencies between entities, i.e. how different entities interact with each other through their attributes : 1→N , N→1 , N→N

• Physical model : create the schema to represent it (flat, relational, star, snowflakes, graph)

Example :