Category: SQL

1. Introduction to SQL Alright, class! Imagine we’re in a cozy classroom in Mumbai on this fine Republic Day afternoon in 2026—maybe with some chai and biscuits on the side. I’m your friendly neighborhood...

SQL Syntax Basics Alright, class! Welcome to Chapter 2 — the place where we stop talking about SQL and actually start speaking it. Think of this as learning the grammar and pronunciation of a...

Think of a database as a big folder (or a filing cabinet) that contains many tables (like spreadsheets inside that folder). One server/computer can hold hundreds or thousands of these databases — each one...

Up until now, we’ve created databases (like empty filing cabinets). Now we’re going to fill them with actual tables — the spreadsheets inside the cabinet where all your data lives. Today we’re going to...

Choosing the right data type for each column is like choosing the right size of box when packing things for a move: Too small → your data gets cut off or you get errors...

Constraints are the rules you place on your columns to make sure the data inside your tables is correct, consistent, and meaningful. Think of them as the “guardrails” that prevent bad data from entering...

Up until now, we’ve been architects: designing databases, creating tables, choosing perfect data types, and adding strong constraints. Now it’s time to become data entry specialists (but the smart, efficient kind 😄). In SQL,...

Almost everything you do in SQL revolves around retrieving data — asking the database questions and getting exactly the answers you need. And the star of this chapter is the SELECT statement — the...

Now we’re going deep into the WHERE clause — the part that lets you filter exactly which rows you want to see. Everything we do here is about writing conditions that the database checks...

Up until now, we’ve been looking at individual rows — one book, one author, one order at a time. Now we’re going to summarize huge amounts of data: How many books do we have...