  We study general correlation functions of various quantum field theories in
the holographic setup. Following the holographic proposal, we investigate
correlation functions via a geodesic length connecting boundary operators. We
show that this holographic description can reproduce the known two- and
three-point functions of conformal field theory. Using this holographic method,
we further study general two-point functions of a two-dimensional thermal CFT
and of a scalar field theory living in a dS or AdS space. Due to the nontrivial
thermal or curvature effect, the two-point functions in an IR limit show
different scaling behaviors from those of the UV CFT. We study such nontrivial
IR scaling behaviors by applying the holographic method.
