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What is a database schema?

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A database schema is an abstraction used to represent the storage of data in a database. It not only describes the organization of data but also represents the relationship between various tables in a database.

Types of database schema

There are two types of database schemas.

Logical database schema: This is best described as a design blueprint of how the data is organized and used by humans (not machines) to meet business requirements.

Physical database schema: This represents how data is actually stored physically on disk storage.

The difference between these two schemas is summarized in the table below.

Difference between logical and physical Database Schema

Types of keys

Primary key: It is used to uniquely identify a record in the table.

Foreign key: It is an attribute that is used as a primary key in another table.

svg viewer
Database schema illustration

The following code snippet defines the schema of a table mapdata in MySQL.

       CREATE TABLE mapdata (
       id integer NOT NULL AUTO_INCREMENT,
       mapid integer NOT NULL,
       x integer NOT NULL,
       y integer NOT NULL,
       z integer NOT NULL,
       value varchar(1),
       UNIQUE KEY(id))

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databases
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