Introduction to PostgreSQL — Complete Guide

Introduction to PostgreSQL — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of PostgreSQL Tutorial on Toolliyo Academy.

8 min read Updated 8/19/2026

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PostgreSQL Tutorial · Lesson 1 of 100

Introduction to PostgreSQL

SQL → Advanced

SQL · 1 — Queries · ~6 min · PostgreSQL — Foundations

What is this?

PostgreSQL is an open-source object-relational database that stores data in tables and speaks SQL. It runs as a server process you connect to with psql or pgAdmin. Unlike a spreadsheet, it handles millions of rows, concurrent users, and strict data rules.

Why should you care?

Flipkart-scale catalogs, Swiggy order pipelines, and Razorpay ledgers rely on PostgreSQL because it combines ACID transactions with rich types like JSONB and arrays.

See it live — copy this example

Run in pgAdmin or psql.

-- Connect to PostgresVerse and inspect the server
\c PostgresVerse
SELECT current_database(), version();

What happened?

The \c command in psql switches your session to PostgresVerse.
current_database() confirms where you are.
version() shows the exact PostgreSQL build so you know which features are available.

Practice next

Open psql or pgAdmin Query Tool and connect as your local superuser.
Run CREATE DATABASE "PostgresVerse"; if it does not exist yet.
Run \c PostgresVerse in psql (or select PostgresVerse in pgAdmin).
Run SELECT current_user, inet_server_addr(), inet_server_port();
List all databases with \l in psql.

Remember

PostgreSQL is a server you connect to, not a file on disk. PostgresVerse is the practice database for this course. Check version() before using newer syntax like MERGE.