Improved maintenance through data independence
In file-based systems, the descriptions of the data and the logic for accessing the data are built into each application program, making the programs dependent on the data. A change to the structure of the data, for example making an address 41 characters instead of 40 characters, or a change to the way the data is stored on disk, can require substantial alterations to the programs that are affected by the change. In contrast, a DBMS separates the data descriptions from the applications, thereby making applications immune to changes in the data descriptions. This is known as data independence and is discussed further in Section 2.1.5. The provision of data independence simplifies database application maintenance.