SQL

7.7    Window Functions

We’ve arrived a topic that will make your life as a developer much easier. Window functions offer the benefit of reducing some calculations into a single query instead of multiple related queries.

In a nutshell, we use window functions to perform calculations across a set of rows that are related to the current row. Window functions are different from aggregate functions in that related rows won’t collapse into a single aggregate row. Instead, each row stays intact and becomes a new calculated column.

This may be hard to imagine before seeing it in action, so let’s review all the window functions to make them understandable.

7.7.1    RANK

For starters, let’s take a look at our product prices via Listing 7.144.

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