How many feng shui dragon veins are there in Chinese legends?

Do you think dragon veins are easy to find? You must know that many emperors in ancient times did not live in Chenglong Vein. There are also differences in dragon veins. For example, Dragonfly Dianshui is a one-time dragon vein and cannot be used again after use. There are also dragon eyes, dragon holes, etc. Legend has it that as long as the bones of one's predecessors are thrown into the dragon's eye, the descendants will be promoted to higher places. As for the dragon's lair, I heard that the famous "hanging coffin" in Sichuan is a dragon's lair. ! !