Linear combinations of atomic orbitals and plane-wave calculations of the electronic structure of the ionic crystal MgO were performed. Local characteristics of the electronic structure of this crystal are obtained using the traditional approaches and the method based on Wannier-type atomic orbitals (WTAOs). It is demonstrated that the results of the conventional methods for chemical bonding analysis in MgO are contradictory and unreasonable. On the contrary, the results of the WTAO method for both types of the basis correctly exhibit the ionic nature of chemical bonding in this crystal.