  In a generic setting of Wess-Zumino models, we prove that the existence of a
supersymmetric vacuum with a vanishing superpotential can be a consequence of a
continuous or discrete R-symmetry when invariant fields are not less than
fields transforming in the same way as the superpotential under the R-symmetry.
The realization in string theory is discussed. We show that a rich landscape of
low energy supersymmetric vacua can be found in the Type IIB flux
compactification setup ready for the KKLT construction of de Sitter vacua in
string theory.
