Every officer provided for in the Charter shall, before entering upon the discharge of the duties of office, take the following oath or affirmation: “I do solemnly swear (or affirm, as the case may be) that I will support the Constitution of the United States and the Constitution of the State of California and the Charter of the City of Los Angeles, and that I will faithfully discharge the duties of the office of (here inserting the name of the office) according to the best of my ability.”