How can I categorize entites by their age in an entity relational diagram? I am designing an entity relational diagram and I need to categorize entities in groups by their age.
What I have is an entity of Person and some personal attributes about it. But I want to have information about people based on their age. For example I want to have have groups for people of age 1-10, 11-20, 21-30 and so on.
Is it possible to design something like this in the entity relation diagram, and if yes how, or is it a bad technique and I should implement it in later stages of the development?
This would be a case for either filtering the data during your query (WHERE clause) or creating a view that already filters it out. In normal practice, a person table is a person table, and unless the fundamental fields are different (like the difference between customers and employees), then all person records go into the same table, and the diagrams reflect that.
When drawing things up, start with just how the data is related across the database, then start worrying about sorting, grouping, and filtering based on the data for when you are planning out stored procedures and views.