Consecutive User Logins - SQL Interview Query 17 | SQL Problem Level "MEDIUM"

A walkthrough of solving a medium-difficulty SQL interview problem: finding users who logged in for five or more consecutive days. The solution uses dense_rank() as a window function to assign group identifiers to consecutive login dates, then aggregates by user and date group, filtering with a HAVING clause based on the difference between min and max login dates. Implementations are shown for both PostgreSQL (using date arithmetic) and SQL Server (using DATEADD and DATEDIFF functions).