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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

Numbering Olympic athletes by medals earned

Row numbering can also be used for ranking. For example, numbering rows and ordering by the count of medals each athlete earned in the OVER clause will assign 1 to the highest-earning medalist, 2 to the second highest-earning medalist, and so on.

Instructions 1/2

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  • For each athlete, count the number of medals he or she has earned.