SQL - Simplify Database

NULL in SQL Explained Simply: IS NULL, COALESCE and Common Traps

Understand what NULL means in SQL, why = NULL never works, and how to handle missing values with IS NULL, COALESCE and NULLIF.

Learn how to use the SQL CASE expression for if/then/else logic: labels, conditional counts, custom sorting and more, with simple examples.

Learn how SQL constraints like NOT NULL, UNIQUE, CHECK and DEFAULT protect your data, with simple examples you can use right away.

A practical guide to SQL data types: numbers, text, dates and more, with differences between SQL Server, MySQL and PostgreSQL.

A beginner-friendly guide to SQL window functions: OVER, PARTITION BY, ROW_NUMBER, RANK, running totals and LAG, with clear examples.

Learn what stored procedures are, how to create and run them in SQL Server, MySQL and PostgreSQL, and when they are worth using.

Learn what a SQL view is, how to create one, and how views simplify queries, improve security and keep reports consistent.

What SQL transactions are, how BEGIN, COMMIT and ROLLBACK work, and what ACID means, explained with a simple bank transfer example.

Learn how to add, change and remove data in SQL with INSERT, UPDATE and DELETE, plus the safety habits that stop costly mistakes.

My pick of the best SQL and database books for every level, from your first query to database design, performance and large-scale data systems.