Ddia-Models-Query-Langs

Data Models and Query Languages

There is a rich history in academia among competing data models, and the resulting winner of the debate was the relational model that most developers in 2022 are familiar with. However, other models are still prevalent today in domains where the relational model can be awkard. These nonrelational NoSQL (read as Not-Only-SQL not No-SQL) approaches largely fall into two categories:

• Document databases are useful when data comes in self-contained "documents" and relationships among those documents are rare.
• Graph databases are useful where anything is potentially related to anything else.

These NoSQL databases differ from the relational model in that there is no schema enforced by the database. Ultimately, this means schema is enforced on read by the application, and not on write by the database.