Subqueries

Summary

A query nested inside another query, used when you need an intermediate result before the final calculation — for example filtering against a computed average.

How to Learn This

1Write a query filtering rows above the average value using a subquery.
2Practice a subquery in the WHERE clause versus one in the FROM clause.
3Learn when a subquery is clearer than a JOIN, and when it isn't.

Joins (INNER, LEFT, RIGHT, FULL)

Common Table Expressions (CTEs)

More topics in SQL for Data Analysis

SQL Basics (SELECT, WHERE, ORDER BY)Aggregate Functions (COUNT, SUM, AVG)GROUP BY & HAVING Joins (INNER, LEFT, RIGHT, FULL)Common Table Expressions (CTEs)Window Functions Date & String Functions Query Optimization Basics Database Design Basics (ER Diagrams)

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