File is a Chinese word with two meanings. In a broad sense, it refers to all kinds of materials with information records produced by organizations or individuals for handling affairs, and in a narrow sense, it refers to official documents used by organs, groups, enterprises and institutions externally and internally. The second refers to a collection of records with the same properties. Meaning refers to all kinds of materials with information records made by organizations or individuals for handling affairs. In a narrow sense, it refers to official documents issued by organs, organizations, enterprises and institutions for internal use. A collection of records of the same nature. According to the different types of records, there are two categories: operating system files and database files. The file in the operating system is only a one-dimensional continuous character sequence, in which the record is only a character group; A file in a database is a collection of structured records, which consists of one or more data items.