03. SQL (Database Management)

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Last Updated: April 22, 2026

advanced sql

Subqueries (Nested Queries) What is a Subquery? A subquery is a query inside another...

Last Updated: April 22, 2026

Definition of JOIN A JOIN is an SQL operation used to combine rows from...

Last Updated: April 22, 2026

What are Aggregate Functions? Aggregate functions:Take multiple rows and return one summarized value Main...

Last Updated: April 22, 2026

Filtering in SQL (WHERE clause) Filtering means:Returning only the rows that match certain conditions...

Last Updated: April 20, 2026

Introduction to Databases (RDBMS) What is a Database? A database is a structured collection...