Start Here: Find Your Learning Path

I’m completely new to databases

Start at the top and work down. Each article builds on the one before it, and you don’t need any technical background.

Prefer a full plan? The Learn SQL Roadmap takes you through 9 stages in order, from your first query to performance tuning, with a tutorial for every step.

1. What is a Database? Explained Simply (Complete Beginner’s Guide)
2. Types of Databases Explained for Beginners (With Real-Life Examples)
3. SQL for Complete Beginners — Your First Queries Explained Simply
4. SQL WHERE, ORDER BY & LIMIT Explained Simply (With Examples)
5. SQL JOINs Explained Simply — Connecting Tables for Beginners
6. SQL GROUP BY & Aggregate Functions Explained Simply
7. SQL vs Excel — What’s the Difference? (And Which One Should You Learn?) (useful if you live in spreadsheets)

I know the basics and want to get better

You can write a SELECT and a JOIN. These are the topics that separate everyday SQL from really good SQL.

1. SQL INSERT, UPDATE and DELETE Explained Simply
2. The SQL CASE Expression Explained Simply (With Examples)
3. NULL in SQL Explained Simply: IS NULL, COALESCE and Common Traps
4. SQL Subqueries vs. CTEs Explained Simply (With Examples)
5. SQL Window Functions Explained Simply (ROW_NUMBER, RANK, LAG and More)
6. SQL Views Explained Simply: What They Are and Why to Use Them

I want to analyse data with SQL

For analysts, report writers and anyone who answers business questions from a database. Work through these in order.

Want the full plan? The SQL for Data Analysis roadmap lays out every step in order, from cleaning data to cohort and funnel analysis, with a tutorial for each one.

1. Data Cleaning in SQL: A Step-by-Step Guide
2. Basic Statistics in SQL: Average, Median, Percentiles and Standard Deviation
3. SQL Window Functions Explained Simply
4. Running Totals in SQL: Cumulative Sums and Running Balances
5. Top N per Group: Get the Latest Record for Each Group
6. SQL Date Functions Explained Simply
7. SQL for Data Analysis: A Step-by-Step Roadmap (what to learn next)

I work with SQL Server

Practical guides for people using Microsoft SQL Server and SQL Server Management Studio day to day.

1. Microsoft SQL Server Explained for Beginners
2. SQL Stored Procedures Explained Simply (SQL Server, MySQL and PostgreSQL)
3. SQL Transactions and ACID Explained Simply (With a Bank Example)
4. SQL Indexes Explained Simply: What They Are and When to Use Them
5. SQL Triggers Explained Simply (With a Price History Example)
6. Database Backup and Restore Explained Simply (SQL Server, MySQL and PostgreSQL)

I’m a Delphi developer

Delphi and SQL Server together are still running a lot of business software. These articles include Delphi (FireDAC and ADO) examples.

1. What Is Delphi? Install Delphi Community Edition and Build Your First App
2. Delphi Basics: Variables, Data Types, If, Case and Loops
3. Why Delphi Is Still a Great Choice for ERP and Business Apps
4. How to Fix Query Timeouts in Delphi + SQL Server Apps
5. SQL Injection: Parameterised Queries (incl. Delphi FireDAC)
6. SQL Transactions and ACID Explained Simply (With a Bank Example)
7. SQL Stored Procedures Explained Simply (SQL Server, MySQL and PostgreSQL)

My queries are slow

Start with indexes, because they fix most slow queries, then work through the rest.

Using SQL Server? Follow the SQL Server Performance Troubleshooting guide: one checklist from “it’s slow” to the real cause, with a deeper article for every step.

1. SQL Indexes Explained Simply: What They Are and When to Use Them
2. How to Fix Query Timeouts in Delphi + SQL Server Apps
3. SQL Data Types Explained Simply: Choosing the Right Type for Each Column
4. SQL Subqueries vs. CTEs Explained Simply (With Examples)
5. How to Read a SQL Server Execution Plan (Beginner’s Guide)
6. SQL Server Parameter Sniffing: Fast in SSMS but Slow in the App
7. SQL Server Blocking: How to Find the Blocking Session

I’m designing a database

Get the structure right before you write a single query. It saves months of clean-up later.

1. Primary Keys vs. Foreign Keys Explained for Beginners
2. Database Normalization Explained Simply: 1NF, 2NF and 3NF With Examples
3. SQL Data Types Explained Simply: Choosing the Right Type for Each Column
4. SQL Constraints Explained Simply: NOT NULL, UNIQUE, CHECK and DEFAULT
5. SQL Transactions and ACID Explained Simply (With a Bank Example)

I’m choosing a database

Not sure whether you need MySQL, PostgreSQL, SQL Server or something else? Read these in order.

1. What is a Database Server? Explained Simply for Beginners
2. How to Choose the Right Database Server for Your Project
3. MySQL Explained for Beginners — What It Is and How It Works
4. PostgreSQL Explained for Beginners — What Makes It Different?
5. MySQL vs PostgreSQL — Which Should You Use?
6. SQL vs. NoSQL: Choosing the Right Database for Your Project

I’m curious about big data

What changes when data gets too big, too fast or too varied for one ordinary database.

1. What is Big Data? Explained Simply for Beginners
2. The Five Vs of Big Data Explained with Real Examples
3. Big Data vs. Data Science vs. Data Analytics: What’s the Difference?
4. Understanding Data Lakes vs. Data Warehouses vs. Data Lakehouses
5. OLTP vs OLAP Explained Simply
6. Star Schema vs Snowflake Schema: Fact and Dimension Tables
7. ETL vs ELT Explained Simply
8. A Beginner’s Guide to the Data Science Lifecycle