RDBMS - Relational Database Management System

What is an RDBMS?

RDBMS stands for relational database management system—a software system that enables you to define, create, maintain, and control access to relational databases. It is the underlying part of the interface layer that helps you store and work with data.

Now let's address the definition of a relational database to see what makes it so special. A relational database is the most popular type of database that stores and provides access to data points that are related to one another. In relational databases, data is arranged and stored in tables consisting of columns and rows. And of course, you have the intuitive and flexible Structured Query Language to manipulate databases.

How does the relational model work?

Like we mentioned above, RDBMS stores data in tables. Each row in a table is a record with a unique ID, which is called primary key. The columns of a table contain attributes of the data. Since each record typically has a value for each attribute, it becomes easy to form flexible relationships between data points.

Let's take a look at the basic notions associated with relational databases.

Primary key is a unique ID that identifies each row of a table.

Foreign key is a field (or multiple fields) in one table that refers to a primary key in another table. It helps establish relations between tables.

View is a virtual table that does not store data; instead, it presents a certain data output that is computed from underlying tables.

Index is a data structure that contains a copy of a column (or multiple columns) from a database table that is ordered to accelerate database retrieval operations on the original column.

Structured Query Language (SQL) is a domain-specific language used for storing, retrieving, and manipulating data—a standard for relational databases.

SQL query is a request for information from an RDBMS. Users write and execute queries to retrieve, add, modify, and delete data from relational databases.

Types of relationships

There are three main types of relationships between tables that ensure the absolute flexibility of the relational database model.

One-to-one relationships

One-to-one relationship is when a single record in table A is related to one (and only one) record in table B.

One-to-many relationships

One-to-many relationship is a bit more complex: a single record in table A is related to multiple records in table B.

Many-to-many relationships

Finally, the most sophisticated example is many-to-many relationship, when multiple records in table A are related to multiple records in table B.

Relational notations

Now that we have described the main types of relationships, we can add a few words on how they are represented on entity-relationship diagrams—via relational notations.

IDEF1X notation

IDEF1X stands for integrated definition for data modeling. Diagrams of this type show entities connected to each other without relationship symbols. The attributes for any entity are listed as part of a table inside each entity shape instead of separate symbols.

IE notation

IE notation (also known as crow's foot notation) uses graphical symbols to show the 'many' side of relationships.

Parent record	Child record	Example
1 (exactly one)	0..N (zero, one, or more)
1 (exactly one)	0..1 (zero or one)
0..1 (zero or one)	0..N (zero, one, or more)
Data 0..1 (zero or one)	0..1 (zero or one)

Key features of RDBMS

Structured and interrelated data

Data in relational databases is stored in a well-structured and easily understandable table format. Meanwhile, versatile relations between tables and the use of SQL to write queries of different complexity contribute to the flexibility of data management.

ACID support

ACID (which comprises Atomicity, Consistency, Isolation, Durability) is a well-known set of properties of database transactions meant to guarantee data validity despite errors, failures, and other possible mishaps. Relational databases deliver full ACID support.

Multi-user access

Relational databases provide multi-user access along with privileges that allow database administrators to have complete control over activities in databases and grant different levels of access to other users.

Ease of use

Besides the overall convenience of storing, accessing, and managing data in tables, we should mention a multitude of database tools that offer intuitive GUIs and make daily development and administration of databases rather easy even for newcomers.

Advantages and disadvantages of RDBMS

The vast capabilities and benefits of relational database management systems make them perfect for modern software solutions. However, there are also several disadvantages to take note of.

The pros:

Flexible data management
Integrity and security of sensitive data
Reliable data storage, easy backup and recovery
Compliance with data protection standards and regulations (such as GDPR)
Fast integration with commercial software and streamlined development cycle

The cons:

Hardware and software costs
Scalability can be pricey
Regular updates of your RDBMS may require regular database maintenance
Effective work with RDBMS requires professional expertise of database developers and administrators

What are the most popular relational databases in 2023?

RDBMS proved to be the optimal choice for data management in software solutions from nearly every business domain. Examples of the most popular relational database management systems include Oracle, MySQL, Microsoft SQL Server, PostgreSQL, SQLite, and MariaDB.

For each of these, there is a variety of database tools that help tackle routine development and administration tasks with ease and convenience.

Oracle Database

Oracle Database is renowned for its overall complexity, rather difficult management, and high costs. However, in exchange it offers high portability and backward compatibility, easy recovery, and excellent performance.

MySQL

MySQL is one of the leading relational database management systems that boasts a huge community. Although MySQL is generally a free and open-source RDBMS, it is also available under a variety of proprietary licenses.

SQL Server

SQL Server is pretty much the world's most advanced commercial RDBMS, developed by Microsoft and perfectly tailored to corporate IT environments. It delivers secure and efficient data storage and an infrastructure with multiple additional services.

PostgreSQL

PostgreSQL is an open-source RDBMS that offers rich functionality, support for a wide variety of data types, and storage of schemaless data. The popularity of PostgreSQL is currently on the rise.

SQLite

SQLite is a fast and compact database engine; not a full-fledged piece of software, but rather a library that can be embedded in applications.

MariaDB

MariaDB is a community-developed and commercially supported fork of MySQL that was designed to get improved performance and stability as well as adhere to the open-source policy. It is worth noting that MariaDB remains a capable drop-in replacement for MySQL.

How to choose the right relational database?

Commercial databases

High licensing costs
On-demand tech support

Regular updates supplied by the vendor
Reasonable for commercial software

Microsoft SQL Server

IBM DB2

Oracle Database

Open-source databases

Open-source licensing
No official support

Large user communities
For commercial and non-profit software

MySQL

MariaDB

SQLite

PostgreSQL

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Database design

You can easily create and manage tables in a visual editor and draw database structures on entity-relationship diagrams.

Drag-and-drop database objects from Database Explorer directly to your diagram
View logical relationships between tables
Create and edit columns, indexes, primary and foreign keys, check constraints, statistics, triggers, and table storage properties
Add and modify database files, set up database options, handle filegroups, and view database DDL
Reverse-engineer SQL databases

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Database development

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Use smart refactoring with auto-correction of references to renamed objects
Compare database schemas and deploy changes across different environments
Handle changes in multiple version control systems
Debug stored procedures, triggers, and functions
Generate full database documentation in several formats

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Testing

The Studios deliver 200+ generators of realistic test data and handy tools to set up automated unit testing.

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Maintain database integrity and data consistency
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Schedule routine tasks for execution from the command line

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Data loading

With our tools, the most versatile data loading and management tools are always at your service.

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Compare table data, analyze differences, and generate reports
Sync table data between source and target databases
Customize and save templates for recurring tasks
Automate your daily operations from the command line

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Data analysis

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Administration and maintenance

Finally, you can effortlessly streamline routine database administration with a set of specialized tools.

Manage user accounts, roles, and permissions
Monitor server performance and eliminate performance bottlenecks in a matter of moments
Back up and restore your databases
Manage and analyze trace results
Find invalid objects across multiple databases
Optimize table

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RDBMS - Relational Database Management System

What is an RDBMS?

How does the relational model work?

Types of relationships

One-to-one relationships

One-to-many relationships

Many-to-many relationships

Relational notations

IDEF1X notation

IE notation

Key features of RDBMS

Structured and interrelated data

ACID support

Multi-user access

Ease of use

Advantages and disadvantages of RDBMS

What are the most popular relational databases in 2023?

Oracle Database

MySQL

SQL Server

PostgreSQL

SQLite

MariaDB

How to choose the right relational database?

Commercial databases

Open-source databases

dbForge Studio: Meet one of the best database management tools on the market

Database design

Database development

Testing

Data loading

Data analysis

Administration and maintenance

Need an all-in-one solution to manage your RDBMS?