SQL

Learn essential data transformation techniques for cleaning, normalizing, and harmonizing data in ETL pipelines.

Introduction SQL Window Functions are powerful tools that allow you to perform calculations across a set of table rows related to the current row without collapsing the result into a single group. Unlike aggregate functions, which summarize data into a single row per group, window functions retain individual rows while applying calculations over a “window” of rows. This guide covers: Different types of window functions PARTITION BY and ORDER BY Real-world use cases What are Window Functions? A window function performs a calculation across a subset (window) of rows related to the current row. It uses the OVER() clause, which defines how the window is partitioned and ordered. ...