Did you design database schemas from scratch? At what level?

Yes, I have designed database schemas from scratch. This usually involves several levels:

• Conceptual modeling — defining the main entities and relationships between them, for example, using ER diagrams.
• Logical modeling — detailing the data structure considering the chosen DBMS, normalization of tables, defining keys and constraints.
• Physical modeling — creating specific tables, indexes, triggers, and other database objects considering performance and platform features.

Depending on the project, I have been involved in all these stages, from requirements analysis to query and structure optimization.