A lamp socket has a casing, a switching contact assembly, a stem assembly, an electric tab, a photo switch, a first electric connector and a second electric connector. The switching contact assembly is mounted in the casing and around the stem assembly. The stem assembly has a pawl. The pawl has multiple surfaces. The electric tab is mounted on two of the surfaces of the pawl and selectively contacts the switching contact assembly. The first electric connector and the second electric connector are connected electrically to the photo switch. The contact between the electric tab and the switching contact assembly switches via turning the stem assembly to turn on or off two lights. Furthermore, the lamp socket turns on one of the lights based on ambient light.