Section 30.  Every official shall take the following oath or affirmation:  “I, .  .  ., do solemnly swear (or affirm) that I will support the constitution and laws of the United States and the constitution and laws of this state and that I will faithfully and impartially discharge and perform all the duties incumbent upon me as .  .  ., according to the best of my ability and understanding, so help me God.”