You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am James Allen.

ASSISTANT: How may I help you?

USER: I want to book a flight ticket from OAK to IAH in the month of September to meet my friend.

ASSISTANT: Sure, I will help you out in booking the ticket.

USER: Thank you.

ASSISTANT: May I know your travelling dates please?

USER: Sure, my travelling dates are 09/09 and 09/11.

ASSISTANT: Can I know your airport codes too?

USER: I have already mentioned.

ASSISTANT: Ok, please wait for a while.

USER: Ok, sure.

ASSISTANT: Sorry, there are no flights found in our database.

USER: Not a problem, anyway thank you for the information.

ASSISTANT: Thank you for choosing us.