A database is a repository for data. It has a large storage space, which can store millions of pieces of data, tens of millions of pieces of data, hundreds of millions of pieces of data. But the database is not random data storage, there are certain rules, otherwise the efficiency of the query will be very low. Today's world is an Internet world full of data, full of a lot of data. The world of the Internet is the world of data. There are many sources of data, such as travel records, consumption records, web pages visited, messages sent and so on. In addition to text type data, images, music, sound are all data