Expert T-SQL Window Functions in SQL Server 2019: The Hidden Secret to Fast Analytic and Reporting Queries

© Kathi Kellenberger, Clayton Groom, and Ed Pollack 2019

K. Kellenberger et al.Expert T-SQL Window Functions in SQL Server 2019https://doi.org/10.1007/978-1-4842-5197-3_6

6. Taking a Peek at Another Row

Kathi Kellenberger¹ , Clayton Groom² and Ed Pollack³

(1)

Edwardsville, IL, USA

(2)

Smithton, IL, USA

(3)

Albany, NY, USA

 

Along with accumulating window aggregates, Microsoft added eight new window functions with SQL Server 2012. Four of the functions, which I’ll call offset functions in this book, are my favorite T-SQL functions, and they are LAG, LEAD, FIRST_VALUE, and LAST_VALUE. These functions let you include any columns from other rows in your results without a self-join and with fantastic performance.

In this chapter, you will learn how to use LAG ...