But both are different from each other.ĭatabase Schema is a representation of a planned database and does not actually contain the data. The terms database schema and database instances are related to each other & sometimes confusing to be used as the same thing. It does not contain any column name or datatype.ĭatabase Instance or Database Schema is the same? It contains the column names and their data types. It also contains both primary & secondary keys. It contains both primary & secondary Keys. Difference between the Physical and Logical Database Schema Physical database schema This schema generally describes the end-user interaction with the database systems. The view level design of a database is known as view schema. The FK represent the foreign key in the diagram. The Foreign key is used as the primary key for other tables. The Ids of the upper three circles are the primary keys. The primary key is used to uniquely identify the entry in a document or record. In the given example, the Ids are given in each circle, and these Ids are primary key & foreign keys. Below is the schema diagram, the simple ER model representing the logical flow of transaction in a commerce application. We can understand it with an example of a basic commerce application. The ER modelling stands for entity-relationship modelling, which specifies the relationships between different entities. Various tools are used to create a logical database schema, and these tools demonstrate the relationships between the component of your data this process is called ER modelling. The logical schema represents how the data is stored in the form of tables and how the attributes of a table are linked together.Īt this level, programmers and administrators work, and the implementation of the data structure is hidden at this level. Here the term integrity constraints define the set of rules that are used by DBMS (Database Management System) to maintain the quality for insertion & update the data. It defines the views, integrity constraints, and table. The Logical database schema specifies all the logical constraints that need to be applied to the stored data. Designing a database at the physical level is called a physical schema. The database schema is divided into three types, which are:Ī physical database schema specifies how the data is stored physically on a storage system or disk storage in the form of Files and Indices. This also represents the relationships between the tables and primary keys as well as foreign keys. It contains three tables, their data types.
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