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  3. PostgreSQL Summary Stats and Window Functions
  • 1

    Introduction to window functions

    Free

    In this chapter, you'll learn what window functions are, and the two basic window function subclauses, ORDER BY and PARTITION BY.

  • 2

    Fetching, ranking, and paging

    In this chapter, you'll learn three practical applications of window functions: fetching values from different parts of the table, ranking rows according to their values, and binning rows into different tables.

  • 3

    Aggregate window functions and frames

    In this chapter, you'll learn how to use aggregate functions you're familiar with, like `AVG()` and `SUM()`, as window functions, as well as how to define frames to change a window function's output.

  • 4

    Beyond window functions

    In this last chapter, you'll learn some techniques and functions that are useful when used together with window functions.

Initializing

Exercise

Reigning champions by gender

You've already fetched the previous year's champion for one event. However, if you have multiple events, genders, or other metrics as columns, you'll need to split your table into partitions to avoid having a champion from one event or gender appear as the previous champion of another event or gender.

Instructions

100 XP
  • Return the previous champions of each year's event by gender.