Data model Schema and Instance


An instance of the database is the data stored in a particular database for a limited time. The storage is for the finite interval of time. When we talk about the overall design of the database, then it is called a schema. It is the skeleton structure of the database, which represents the logical outlook of the complete mentioned database. A schema consists of some schema objects such as – table, primary key, foreign key, columns, views, stored procedure, data types, etc.

A database schema can also be in the form of visual diagrams. The diagram reflects all the database objects and their relationship with each one of them. The design of the database schema represents the designs of the database designers that can help the programmers. The software of these programs will interact with the respective database, and the process of the database creation is indeed known as data modeling.

The property of a schema diagram is that it can display only some of the aspects of a schema. The elements cover the name of data type, constraints, and record type. Other factors can’t be in specification with the help of a schema diagram. For example, in the given figure, there is no data type of every data item and no relationship between the different files.

The actual data of the database change at a regular rate; for example, in the other figure, the database changes whenever we try to add a new grade.

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