How to calculate the cumulative distribution of the sorting field expression in the current result set window using the CUME_DIST() function?

CUME_DIST() is a MySQL built-in window function that calculates the cumulative distribution of the sorting field expression in the current result set window. For example:

SELECT help_topic_id, help_category_id,
  CUME_DIST() OVER w
  FROM mysql.help_topic
  WINDOW w AS (ORDER BY help_category_id);
  -- +---------------+------------------+----------------------+
  -- | help_topic_id | help_category_id | CUME_DIST() OVER w   |
  -- +---------------+------------------+----------------------+
  -- |             0 |                1 | 0.002932551319648094 |
  -- |             1 |                1 | 0.002932551319648094 |
  -- |             2 |                2 | 0.054252199413489736 |
  -- |             6 |                2 | 0.054252199413489736 |
  -- |             7 |                2 | 0.054252199413489736 |
  -- |             8 |                2 | 0.054252199413489736 |
  -- |             9 |                2 | 0.054252199413489736 |
  -- ...
  -- +---------------+------------------+----------------------+

Reference information of the CUME_DIST() function:

CUME_DIST(): val
  Returns the cumulative distribution of the sorting field expression
  in the current result set window.

Arguments, return value and availability:
  val: Return value. The cumulative distribution of the sorting field.
  Available since MySQL 8.

Related MySQL functions:

• CUME_DIST() - Cumulative Distribution of Sorted Values
• DENSE_RANK() - Density Rank of Sorted Values
• PERCENT_RANK() - Rank Percentage of Sorted Values
• RANK() - Vale Rank of Sorted Values

⇒ DENSE_RANK() - Density Rank of Sorted Values

⇐ MySQL Functions on Result Set Windows

⇑ MySQL Functions on Result Set Windows

⇑⇑ MySQL Function References