Mastering SQL Joins and Window Functions

Introduction SQL joins are used to combine rows from two or more tables based on related columns, while window functions perform calculations across a set of related rows within a single result set without collapsing individual rows. In this article, we'll break down these two in a practical way showing their use in analytics, backend systems and data projects. SQL Joins A JOIN combines rows from two or more tables based on a related column between them.They help in: Retrieving connected data stored across multiple tables. Matching records using common columns. Improving data analysis by combining related information. Creating meaningful result sets from separate tables. We'll use the following 2 tables: Customers | customer_id | name | | ----------- | ----- | | 1 | Alice | | 2 | Bob | | 3 | Carol | Orders | order_id | customer_id | amount | | -------- | ----------- | ------ | | 101 | 1 | 250 | | 102 | 1 | 300 | | 103 | 2 | 150 | 1. INNER JOIN Is used to retrieve rows where matching va