A window function, also known as an analytic function in SQL, is a function that returns a result for each row using values from one or more rows.
Analytic functions use a group of rows to calculate an aggregate value. Analytic functions, unlike aggregate functions, can return numerous rows for each group. To compute moving averages, running totals, percentages, or top-N outcomes inside a group, use analytic functions.
Users can utilise window functions to do calculations on partitions (also known as subgroups or sections) of a result set, such as a table or the results of another query.
Because they work with a "window frame" — a collection of rows related to the current row that may be specified more precisely with the ROWS or RANGE keywords.
Two functions that you can nest as an argument of a window aggregate function are referred to as nested window functions. The nested row number function and the nested value of expression at row function are the two functions.
