Design and process
Over the years, many books have been written about modeling and designing database systems. However, many of these books fail to make the connection between technicality and practicality—which are inextricably linked. Often, modeling books prioritize completeness—such as describing four different notations to express a relationship—and ignore usability (e.g., which notation would be most accessible to business users?).
The most significant complexity of a database system is not technical. It is the business model itself—the interactions within a business and the rules that govern them. If the business model is not aligned with the data model, the database will be repeatedly forced to adjust (while losing organizational trust and resources in the process.)
What is needed is a business-readable language that developers use to build and document the database landscape.