How To Use Window Functions in SQL
When it comes to quantitative analysis on data in database tables standard SQL provides a set of aggregate functions like SUM(), MAX(), and MIN(). There are two main ways these functions get used in practice: (i) collapsing the table data down to represent the aggregate calculation result set or, (ii) presenting the aggregate calculation per row maintaining the granularity of the complete table. Windowing functions are used to accomplish this second option and will the focus of this article.
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