Gym Management System ER diagram models a complete membership lifecycle with 16 interconnected entities spanning members, trainers, subscriptions, payments, and attendance tracking. The schema normalizes member profiles through the People table, linking to Members for membership status and Subscriptions for active plans, while Trainers connect via Specializations and EmploymentStatuses. Payment processing flows through Subscriptions to Payments, supporting multiple PaymentMethods and PaymentStatuses, and daily operations are captured via Attendances with CheckIn/CheckOut timestamps. This relational design enforces data integrity through foreign keys and lookup tables (MembershipStatuses, AvailabilityStatuses, AccountStatuses), enabling gyms to track member lifecycles, trainer assignments, and revenue with minimal redundancy. Fork this diagram on Diagrams.so to customize for your gym's specific roles, pricing tiers, or reporting needs. The modular status tables allow easy extension for new membership types or payment workflows without schema restructuring.