Finding Top n Elements in Pandas DataFrame Column by Keeping the Grouping

Grouping by Series or Sequence in R Using data.table Library

Mastering Group by and Conditional Count in R's dplyr Library: A Deep Dive

Finding Equal Row Sets Across Different Tables in SQL Server Using the FOR XML Trick or Alternative Approaches

Counting Distinct IDs for Each Day within the Last 7 Days using SQL

Applying .GRP to Multiple Columns in data.table R for Separate Grouping

Understanding Crosstabulation Limitations: How to Apply Ranges in R for Accurate Analysis