A database engine can sort, change or serve the information on the database. The information itself can be stored in many different ways - before digital computers, card files, printed books and other methods were used. Now most data is kept on computer files.
A database system is a computer program for managing electronic databases. A very simple example of a database system would be an electronic address book.
The data in a database is organized in some way. Before there were computers, employee data was often kept in file cabinets. There was usually one card for each employee. On the card, information such as the date of birth or the name of the employee could be found. A database also has such "cards". To the user, the card will look the same as it did in old times, only this time it will be on the screen. To the computer, the information on the card can be stored in different ways. Each of these ways is known as a database model. The most commonly used database model is called relational database model; it uses relations and sets to store the data.

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