Schema in DBMS

In this course, we will study schema, its types-physical, logical and view, and advantages and disadvantages of the database schema.

What is the schema in DBMS

The term schema refers to the organization of data in the form of a blueprint of how the database is constructed that is divided into database tables in the case of a relational database. The formal definition of a database schema is a set of formulas or sentences called as integrity constraints that are imposed on a database. The integrity constraints are there to ensure the compatibility between parts of the schema. The schema can be categorized into three categories. Which are:

  1. Physical or internal schema
  2. Logical or conceptual schema
  3. View or external schema
Schema in DBMS

Physical schema

A physical schema can define the design of a database at the physical level. It is also known as the internal level or schema.

Logical schema

A logical schema can be defined as the designing of the database at the logical level. It is also known as a conceptual level or schema.

View schema

On an external level, we are only concerned about the data which is viewed by specific end users. It is also known as the external level or schema.

What are the advantages of database schema

Management of data independent of the physical storage can be done. Migration to new graphical environments can now be done fast.

What are the disadvantages of database schema

The complete database Schema is a very complex structure and is difficult to be understood by everyone. Setup and Maintenance is difficult.
The physical separation of the tiers may affect the performance of the Database.