Briefly describe the characteristics of database systems.

①Data structuring: database systems achieve overall data structuring, which is one of the main characteristics of the database, but also the main difference between database systems and file systems. This structuring means that the data in the database is no longer only for a particular application, but for the whole system; database, not only the data is structured internally, but also the whole is structured, and the data has a link between them. ② high data **** enjoyment, low redundancy, easy to expand: because the data is no longer for a particular application, but for the entire system, so the data can be different users and different applications **** enjoyment, which reduces the redundancy of the data, saving storage space, easy to increase the number of new applications, making it easy to expand the database system. ③ High data independence: data independence including physical independence and logical independence, the database system through the second level of mapping to achieve these two kinds of independence. ④ data management and control by the database management system: the database provides four aspects of data control functions, respectively, data security protection, data integrity checks, concurrency control and database recovery.