SQL Queries - 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.

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

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

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

Understand the difference between SQL subqueries and CTEs (WITH clauses), when to use each, and how they affect readability and performance.

Learn how to filter, sort and limit query results in SQL with WHERE, ORDER BY and LIMIT, using simple real-world examples.

You’ve learned how to fetch rows, filter them, and join tables together. But what if you don’t want individual rows

If you’ve started learning SQL, you’ve probably hit the same wall every beginner hits: JOINs. They look complicated. The diagrams