Running Totals from Consecutive Columns: A Flexible Approach to Gaps and Islands

Handling Missing Primary Keys for Derived Columns: The LAG/LEAD Puzzle in SQL Server 2012

Fixing Discontinuous Date Ranges with Oracle SQL: A Step-by-Step Guide

Grouping Consecutive Rows Based on One Column Using SQL Row Number Functions

Solving Duplicates in Time Periods from Repeated Groups Using SQL Analytics