The CUME_DIST function is a built-in analytical function in the Oracle database that calculates the cumulative distribution of a value within a group of values. This function is often used in statistical analysis and can be very useful in business intelligence applications.
The syntax of the CUME_DIST function is as follows:
CUME_DIST(expression) OVER (ORDER BY expression [ASC | DESC])
Where expression is the value that you want to calculate the cumulative distribution for, and the ORDER BY clause is used to specify the order in which the values are evaluated. The optional ASC or DESC keywords can be used to specify whether the values should be sorted in ascending or descending order.
The CUME_DIST function returns a value between 0 and 1, which represents the cumulative distribution of the expression within the group of values. For example, if the CUME_DIST function returns a value of 0.5 for a given value, it means that the value is greater than or equal to 50% of the other values in the group.
Here is an example of how to use the CUME_DIST function in PL/SQL:
SELECT department, salary, CUME_DIST() OVER (PARTITION BY department ORDER BY salary) AS cum_dist FROM employees;
This query calculates the cumulative distribution of employee salaries within each department. The PARTITION BY clause is used to group the salaries by department, and the ORDER BY clause is used to sort the salaries in ascending order. The CUME_DIST function is then used to calculate the cumulative distribution of each salary value within its respective department.
In conclusion, the CUME_DIST function in Oracle’s PL/SQL language is a useful tool for analyzing the distribution of values within a group. By using this function, you can gain valuable insights into the data and make more informed decisions.