i need ER digram for this qustion without primiry key  DB for Railway Reservation  Purpose: The Database is for a railway reservation system which facilitates the passengers to enquire about the trains available on the basis of source and destination, booking and cancellation of tickets, enquire about the status of the booked ticket, etc. The database is for maintaining the records of different trains, train status, and passengers. The record of train includes its number, name, source, destination, and days on which it is available, whereas record of train status includes dates for which tickets can be booked, total number of seats available, and number of seats already booked. Passengers can book their tickets for the train in which seats are available. For this, passenger has to provide the desired train number and the date for which ticket is to be booked. Before booking a ticket for a passenger, the validity of train number and booking date is checked. Once the train number and booking date are validated, it is checked whether the seat is available. If yes, the ticket is booked with confirm status and corresponding ticket ID is generated which is stored along with other details of the passenger. After all the available tickets are booked, certain numbers of tickets arebooked with waiting status. If waiting lot is also finished, then tickets are not booked and a message of non availability of seats is displayed. The ticket once booked can be ‐ cancelled at any time. For this, the passenger has to provide the ticket ID (the unique key). The ticket ID is searched and the corresponding record is deleted. With this, the first ticket with waiting status also gets confirmed

i need ER digram for this qustion without primiry key 

DB for Railway Reservation 
Purpose: The Database is for a railway reservation system which facilitates the
passengers to enquire about the trains available on the basis of source and destination,
booking and cancellation of tickets, enquire about the status of the booked ticket, etc.
The database is for maintaining the records of different trains, train status, and
passengers. The record of train includes its number, name, source, destination, and days
on which it is available, whereas record of train status includes dates for which tickets
can be booked, total number of seats available, and number of seats already booked.
Passengers can book their tickets for the train in which seats are available. For this,
passenger has to provide the desired train number and the date for which ticket is to be
booked. Before booking a ticket for a passenger, the validity of train number and
booking date is checked. Once the train number and booking date are validated, it is
checked whether the seat is available. If yes, the ticket is booked with confirm status
and corresponding ticket ID is generated which is stored along with other details of the
passenger. After all the available tickets are booked, certain numbers of tickets arebooked with waiting status. If waiting lot is also finished, then tickets are not booked
and a message of non availability of seats is displayed. The ticket once booked can be ‐
cancelled at any time. For this, the passenger has to provide the ticket ID (the unique
key). The ticket ID is searched and the corresponding record is deleted. With this, the
first ticket with waiting status also gets confirmed.