CodingNic
Sign In Book Session

Database and PostgreSQL Foundations

DBMS and RDBMS

Database and PostgreSQL Foundations 10 min read

DBMS and RDBMS

Objectives

By the end of this lesson, you should be able to:

  • Explain what a DBMS is
  • Explain what makes an RDBMS specifically “relational”
  • Describe what a table, row, and column are

💡 Why this matters: “Database” describes the data itself, but you need actual software to store it, protect it, and answer questions about it. That software is a DBMS, and the specific kind this entire course is built around is an RDBMS.

What Is a DBMS?

A DBMS (Database Management System) is software that creates, stores, and manages databases, handling the actual work of saving data safely, letting multiple people use it at once, and answering queries. When people say “the database,” they usually mean a DBMS running somewhere, holding their data.

There are different families of DBMS, built around different ways of organizing data. This course focuses on one specific, extremely common family: the relational kind.

What Makes an RDBMS “Relational”

An RDBMS (Relational Database Management System) organizes data into tables. A table looks a lot like a spreadsheet: rows going down, columns going across.

text
authors
+----+----------------+----------------+
| id | name           | country        |
+----+----------------+----------------+
| 1  | Elena Cross    | United States  |
| 2  | Marcus Delaney | United Kingdom |
+----+----------------+----------------+

Each row is one record, one specific author, in this case. Each column is one piece of information every row has: every author has a name and a country.

The “relational” part comes from how tables connect to each other. Instead of cramming every book’s author name, country, and biography directly onto every book’s row (repeating it, and risking it going out of sync), a relational database gives authors their own table, and has each book simply point to which author wrote it:

text
authors                              books
+----+----------------+              +-------------------+----------------+
| id | name           |              | title             | author         |
+----+----------------+              +-------------------+----------------+
| 1  | Elena Cross    |  <---------- | The Glass Orchard | Elena Cross    |
| 2  | Marcus Delaney |              | Coastal Light      | Marcus Delaney |
+----+----------------+              +-------------------+----------------+

This pointer between tables is called a relationship, hence “relational” database. Relationships, and exactly how this pointer works, get a full module later in this course, for now the important idea is this: an RDBMS is built around splitting data into related tables instead of duplicating it everywhere.

Common RDBMSs

PostgreSQL isn’t the only RDBMS. A few others you’ll hear about:

  • MySQL (and its close relative MariaDB), historically popular for web applications.
  • SQLite, a lightweight, file-based database with no separate server process, often embedded directly inside mobile apps.
  • Microsoft SQL Server and Oracle Database, commercial (paid) RDBMSs common in large enterprise environments.

They’re different products, but they all speak the same core language, SQL, covered next lesson. What you learn in this course transfers directly to any of them.

Try It

  1. In your own words, explain the difference between “a database” and “a DBMS.”
  2. Explain what makes an RDBMS specifically “relational,” rather than just “a DBMS.”
  3. Name one RDBMS other than PostgreSQL, and one thing it’s commonly known for.

Recap

  • A DBMS is software that creates, stores, and manages databases, protecting data and answering queries.
  • An RDBMS organizes data into related tables (rows and columns), splitting data apart instead of duplicating it, and connecting tables with relationships.
  • PostgreSQL, MySQL/MariaDB, SQLite, SQL Server, and Oracle are all RDBMSs, sharing a large common core of SQL.

Next lesson: SQL itself, the language every RDBMS understands.