In order to connect a water-bearing pipeline of a shower device on a wall, a cannula is suggested to be connected on a joint of two pipeline portions which form a pipeline, and the cannula encompasses a bottleneck which extends out of the end portion of one pipeline portion and gets into another pipeline portion. The cannula can not be replaced to be axially fixed on the bottleneck, but can rotate around the bottleneck. A screw in a groove of the bottleneck can be used to axially and rotatably fix the cannula, and the front end of the screw extends into the cannla.