What is Database Schema?
A database schema is a logical and visual representation of all the elements and their relationships in a relational database.
It provides the architectural design of systematically organized data in a database, which helps stakeholders with effective data communication.
Database schemas, depicted as schema diagrams, contain descriptive details of data and their relations.
Database Schema Design
Database schema has a significant impact on the functioning of a database. It determines how efficiently the database works and how fast you can retrieve data. It also helps in organizing massive amounts of data.
The process of designing a database schema is known as data modeling. Database designers create schemas to present a logical view of the information in a database.
In a relational database, data is in tables, rows, and columns format. A database schema design organizes this data into entities and establishes relationships between entities.
It makes understanding and using information easy. A database schema design contains schema objects – the logical structures. They include:
- Tables
- Fields
- Packages
- Functions
- Keys
- Relationships
Types of Database Schema
There are three common types of database schema design:
Conceptual Database Schema
In conceptual database schema, the design presentation describes only the main concepts of the database and the relations between them. It does not give details of tables, rows, columns, and views.
The purpose of a conceptual database schema is to give an overall view of the database structure and its relationships. A user can understand the underlying structure of the database.
Designers can use the conceptual schema to design more detailed databases.
Logical Database Schema
It is an intermediate between conceptual and physical schema. Logical schema is less abstract than conceptual schema. It describes information in detail by defining data into objects like tables, fields, and columns.
Further, it defines entity relationships and integrity constraints. The purpose of a logical schema is to organize data logically. It typically does not include the technical requirements of the database.
Physical Database Schema
It is the most comprehensive database design. A physical database schema details how information is stored physically on a system. It delineates data into files and indices.
The physical schema also contains information about the storage media, like whether it is a cloud database or something else.
The purpose of a physical schema is to provide detailed information about the physical storage of data to the developer.
Types of Database Schema Designs
An effective database schema design ensures the high performance of a database with minimal resource usage. There are six options for designing database schemas.
The kind of design depends on the requirements of a business. The six database schema designs are:
Flat Model
This schema design organizes data into a two-dimensional array similar to spreadsheets. It is suitable for simple databases without complex data relations.
Hierarchical Model
The design structure of a hierarchical model is similar to a tree structure. It has many child nodes branching from a root or a parent node. Here, the relationships between data is one-to-many.
Network Model
This is similar to a hierarchical model but with many-to-many relationships.
Relational Model
Relational schema design is similar to the flat model, where data is organized into tables, rows, and columns but with the relations among entities clearly defined.
Star Schema
This is suitable for storing large amounts of data. In this model, data is organized into facts and dimensions tables.
Snowflake Schema
This is similar to the star schema but with a change. Dimension tables can have more dimension tables, expanding the descriptiveness of the schema.
Benefits of Database Schema
Poor data organization makes it difficult to maintain and administer a database. An efficient schema ensures the smooth functioning of a database. The benefits of database schema are:
Organized and Consistent Data
Database schema ensures orderly and consistent data by preventing duplication. As the schema provides a logical outline for data, it is a common source of truth for all stakeholders.
Better Communication
Database schema facilitates efficient organization and accurate data documentation that allows all stakeholders to communicate efficiently. Database engineers, administrators, and analysts can easily navigate the data structures.
Improved Performance
The database schema helps in faster data retrieval, enabling quicker operations and reducing strain on resources.
Security and Control
As database schema organizes data into separate entities, restricting data access becomes easy. You can store sensitive information in an entity and control access via permissions. Also, the schema allows for various authentications, encryption, hacking, and other security measures that protect it from hacks and prevent unauthorized access.