The PL/SQL NTILE function is a built-in function in the Oracle database that allows you to divide a result set into a specified number of groups or buckets. It is often used in conjunction with the ORDER BY clause to sort the result set and divide it into equal-sized groups.
The syntax for the NTILE function is as follows:
NTILE(n) OVER (ORDER BY expression)
where n is the number of buckets you want to divide the result set into, and expression is the column or expression you want to sort the result set by.
For example, suppose you have a table called employees with columns employee_id, first_name, last_name, and salary. You want to divide the employees into three groups based on their salary, with each group containing roughly the same number of employees.
You can use the NTILE function as follows:
SELECT employee_id, first_name, last_name, salary, NTILE(3) OVER (ORDER BY salary) as salary_bucket FROM employees;
This will divide the employees into three salary buckets based on their salary, with each bucket containing roughly the same number of employees. The salary_bucket column will contain a value from 1 to 3 indicating which bucket the employee falls into.
Note that the NTILE function requires the use of the OVER clause and can only be used in the SELECT statement of a query. It is commonly used for data analytics and reporting purposes, such as when you want to analyze the distribution of a particular column or variable in your data.