It shall be unlawful for any person, either by himself or his agent, or any person acting as agent, barkeeper, clerk or servant of another, to sell or offer for sale at retail in the City any alcoholic liquor without first having obtained a license so to do as provided in this chapter. It shall likewise be unlawful for any such person to sell or offer for sale any intoxicating liquors, alcoholic or malt or vinous beverages in violation of the terms and conditions of such license. (1961 Code § 4-12)