Tabla: Employee (PK)
─── EmployeeId / ReportsTo ───>
Tabla: Employee (Recursiva)
Tabla: Employee (PK)
─── EmployeeId = SupportRepId ─>
Tabla: Customer (FK)
Tabla: Customer (PK)
─── CustomerId (INTEGER) ───>
Tabla: Invoice (FK)
Tabla: Invoice (PK)
─── InvoiceId (INTEGER) ───>
Tabla: InvoiceLine (FK)
Tabla: Track (PK)
─── TrackId (INTEGER) ───>
Tabla: InvoiceLine (FK)