LCAO and plane wave (PW) DFT calculations of the electronic structure of the ionic crystal MgO are 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 for the first time that the results of the WTAO population analysis for both types of the basis (LCAO and PW) correctly exhibit the ionic nature of chemical bonding in this crystal.