Hospital Management System ER diagram models core clinical operations through six interconnected entities: PATIENT, DOCTOR, APPOINTMENT, DEPARTMENT, and PRESCRIPTION. Relationships flow from PATIENT and DOCTOR through APPOINTMENT to PRESCRIPTION, with DEPARTMENT governing doctor assignments via foreign key constraints. This normalized schema enforces referential integrity, separates concerns across clinical workflows, and supports queries for patient history, doctor schedules, and medication tracking. Fork and customize this diagram on Diagrams.so to adapt it for your hospital's specific departments, additional entities like billing or lab results, or to export as .drawio for use in database design tools. The mandatory/optional relationship indicators (solid/dashed lines) clarify which associations must exist versus those that may be null.