SQL (implementation agnostic)

Developing Time-Oriented Database Applications in SQL

Richard T. Snodgrass

Essential SQL

Krzysztof Kowalczyk, Stack Overflow Documentation project (HTML) (CC BY

How to Design Structured Database Systems Using SQL

Daniel García Solla, freeCodeCamp

Introduction to SQL

PDF)

Learning SQL

Compiled from StackOverflow Documentation

Oracle Database Notes for Professionals

Oracle8i Concepts: Chapter 15 - SQL and PL/SQL

Cathy Baird (HTML)

SQL For Web Nerds

Philip Greenspun

SQL Notes for Professionals

Compiled from StackOverflow Documentation

SQL Queries Succinctly

Nick Harrison

SQL Tutorial

Scaler

SQLite Tutorial

The SQL Handbook

Lane Wagner

Use The Index, Luke!: A Guide To SQL Database Performance

Markus Winand