"Nie wiem, co bym chciał."

Translation: I do not know what I would like.

[Clarence.Victor]

A question about something I have been wondering. The use of commas seems to be different from English. Why is a comma used in this Polish sentence?

[Jellei]

It introduces the second clause.

[fmarkom]

Is "bym chciał " equal to "chciałbym" or is there any specific rule when to use that form?

[Jellei]

I'd say that mostly we avoid putting "bym" at the beginning (so "Chciałbym..." or possibly "Ja bym chciał...", but not just "Bym chciał..."), and at the end (so that's why here we prefer "bym chciał" to "chciałbym").

Generally, "chciałbym" seems more common to me.

[eggers7]

What would be a typical context or situation to say this in Polish - e. g. sitting in a bar and wonder whether to have beer or wine?

[Jellei]

Possibly. I guess any 'I don't know what I want' situation.