i have one table for all person (with fields ex. name, last name) because each person can has one or more role (customer, lead/prospect, supplier, employee). And i have tables (customers, leads, suplliers, employees) for each role with custom fields. Also I have a roles table and a table for person and his roles.
Is correct save leads/prospects in the same person table? Because i can get thousands of leads. But this can down sql query performance?
Other question, some person (customer and employee) can be a user (can be login). Then i create other table named users, but the email is saved in person table. I can use a username for login but i want too the users can login with email.
What do i? I use only use username (in user table), other option copy email (from person table) to user table or for last option a query using the two tables: person and user?