SQL Basics

Introduction to SQL

The language every database speaks — and why you should too

SELECT Statement

Control exactly which columns appear in your output

WHERE Clause

Filter rows — get only the data you actually need

AND Operator

Require multiple conditions to all be true at once

OR Operator

Match rows where at least one condition is true

ORDER BY

Sort results by any column — ascending, descending, or both

LIMIT & OFFSET

Cap the number of rows returned — and paginate through results

Working with NULL

The most misunderstood concept in SQL — and how to handle it

CREATE TABLE

Define a table — columns, types, and the constraints that keep data clean

INSERT Statement

Add new rows — one, many, or copied from another query

UPDATE & DELETE

Change and remove rows — and why WHERE is not optional

ALTER TABLE & DROP TABLE

Evolve your schema — add columns, rename tables, clean up