Asking Question

[kahhong]

Hello there, how to ask people "someone sit beside him or her or not?

[Tdol]

Is anyone sitting beside him/her?

[rewboss]

Or perhaps: "Is anyone sitting next to you?"

If you're asking about the best way to ask if you may sit in a particular seat, I think the most polite and idiomatically natural question might be: "Is this seat taken?"