I have seen in my past experience that most of the people don't use physical relationships in tables and they try to remember them and apply them through coding only.
Here 'Physical Relationships' refer to Primary Key, Foreign Key, Check constraints, etc.
While designing a database, people try to normalize the database on paper and keep things documented. Like, if I have to create a database for a marketing company, I will try to understand its requirements. For example, what fields are mandatory, what fields will contain only (a or b or c) etc.
When all the things are clear, then why are most of the people afraid of the constraints?
- Don't they want to manage things?
- Do they have a lack of knowledge (which I don't think is so)?
- Are they not confident about future problems?
- Is it really a tough job managing all these entities?
What is the reason in your opinion?