O'Reilly logo

Microsoft® SQL Server® 2012 High-Performance T-SQL Using Window Functions by Itzik Ben-Gan

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Chapter 1. SQL Windowing

Window functions are functions applied to sets of rows defined by a clause called OVER. They are used mainly for analytical purposes allowing you to calculate running totals, calculate moving averages, identify gaps and islands in your data, and perform many other computations. These functions are based on an amazingly profound concept in standard SQL (which is both an ISO and ANSI standard)—the concept of windowing. The idea behind this concept is to allow you to apply various calculations to a set, or window, of rows and return a single value. Window functions can help to solve a wide variety of querying tasks by helping you express set calculations more easily, intuitively, and efficiently than ever before.

There are ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required