Be it further enacted, that every officer, agent, and employee holding a position upon an annual salary shall, before entering upon his duties, take and subscribe and file with the clerk, an oath or affirmation that he has all the qualifications named in this charter for the office or employment he is about to assume, that he will support the constitution of the United States and of this state and the charter and ordinances of the city and that he will faithfully discharge the duties of his office or employment. (As amended by Priv. Acts 1972, ch. 416, sec. 7, Priv. Acts 1995, ch. 55, sec. 4, and Priv. Acts 2014, ch. 55, sec. 1)