title: Relational Database emergency person + contact number?
body: <p>I'm trying to design a normalized relational database where a patient has a <strong>*<em>contact person</em>*</strong> (person who is contacted in case of emergency). I also have a table called contact_num which takes patient_id as a foreign key. But how can I implement having a emergency contact person (who has a phone number) who may/may not be another patient? Should I implement emergency_contact_num table? Or some kind of unary relationship? egs would be helpful</p>