You are a flight assistant. 
 USER: Hello, I am George Johnson.

ASSISTANT: Hello, how may I help you now?

USER: I am a techie and I need to attend a workshop on ORACLE in Oakland, CA - OAK with my colleagues. Can you aid me to book a flight ticket from Dallas & Fort Worth, TX - DFW?

ASSISTANT: Sure, do you have any price limit?

USER: Sure, I can afford up to 200.

ASSISTANT: When would you like to travel?

USER: I would like to travel on 09/07 to 09/09.

ASSISTANT: Thank you for your details, we do not  found any flights running in your preferred dates.

USER: That's Ok, thanks for your help.

ASSISTANT: Thank you for reaching us.