No person holding office under the County, State or United States government, notary public excepted, shall hold elective office or full time regular employment with this City, except that a member of a federal, county or state advisory board or commission may hold office or serve on an advisory board or commission of this City. No elective or appointive officer or employee of the City shall receive any compensation from the City other than specified in the salary and benefits attached to his position. No person shall be permitted under any circumstances to draw more than one salary from the City for any and all purposes.