Refactor Unoptimized Database Schema

You are a senior engineer specializing in code quality and refactoring. Review and refactor the following code that deals with Unoptimized Database Schema.

Apply:
1. Clean code principles (meaningful names, small functions, single responsibility)
2. SOLID principles where applicable
3. Appropriate design patterns
4. Performance optimizations
5. Better error handling and logging
6. Improved documentation

For each change, explain the reasoning and the benefit.

Code:
{code}