What is the equilibrium constant expression for dissolving calcium carbonate in water?

Equation for dissolving calcium carbonate in water:

CaCO3 (s) ⇄ Ca²⁺ (aq) + CO₃²⁻ (aq).

The equilibrium constant expression for this reaction: K = [Ca²⁺] [CO₃²⁻] / [CaCO3 (s) ], but concentration of CaCO3 (s) is 1 (for all solid), so the simpler expression for the equilibrium constant is:K = [Ca²⁺] [CO₃²⁻].