Schema in computer science

Schema 👇 

  

👉🏻Schema is logical representation of a data base.It is also known as entity type. Schema like a structure in which one or many tables lie.

 E.g. :- 👉🏻

       Student(AGE,ROLL NO.,REG.NO.,CLASS)  

Here Student is an entity & other materials are attributes.

 

📚🗃️Now talking about  

How many types of schema :-

 

There are three types of schema:-

(i) View  Schema

(ii) Conceptual Schema 

(iii) Physical Schema 

View schema:-( External level schema):-

👉It is also known as View level. View schema defines the design of database at the view level of data abstraction.

It defines how an end user will intract with the database system.

(There are many view schemas for database system .Every schema defines a specific group of data. 

In other words we say like a Student entity represent specific attributes and other entities like Faculty, Infrastructure and so on represents specific data. But similarly these all are connected to college or school management system)

(ii)Conceptual Schema:-   

👉It is also known as Logical schema.

By which way we represents data or we stores data is called conceptual view. 

e.g. :-  

E-R Diagram or E-R model 

relational model tables

(It is like a blue print )

(iii) PHYSICAL VIEW (or Schema)  :-

👉It is also known as internal schema

In actually where data is stored , and that data is stored in which files and size of files and these are stored in which hard disk. That hard disk is totally depends on physical schema. 

(where data is physically present )

Here DBA are present that decides which data to keep in which particular location or in which file, disk ,drive  , how to store and how to fregment.