| --- |
| { |
| "title": "NTILE", |
| "language": "en", |
| "description": "NTILE() is a window function that divides an ordered dataset into a specified number of approximately equal buckets." |
| } |
| --- |
| |
| ## Description |
| |
| NTILE() is a window function that divides an ordered dataset into a specified number of approximately equal buckets. The buckets are numbered sequentially starting from 1 up to the specified number of buckets. When data cannot be divided equally, extra records are allocated to lower-numbered buckets, ensuring that the number of rows in each bucket differs by at most 1. |
| |
| ## Syntax |
| |
| ```sql |
| NTILE( <constant_value> ) |
| ``` |
| |
| ## Parameters |
| | Parameter | Description | |
| | -------------- | --------------------------------------------------------------------------------------------------------------------------- | |
| | constant_value | Required. Specifies the number of buckets to create, must be a positive integer |
| |
| ## Return Value |
| |
| Returns a BIGINT bucket number, ranging from 1 to the specified number of buckets. |
| |
| ## Usage Notes |
| |
| If a statement contains both an ORDER BY clause in the NTILE function and an ORDER BY clause for the output results, these two sorts are independent: |
| - The ORDER BY in the NTILE function determines which bucket each row is assigned to |
| - The output ORDER BY determines the display order of the results |
| |
| ## Examples |
| |
| ```sql |
| SELECT |
| name, |
| score, |
| NTILE(4) OVER (ORDER BY score DESC) as quarter |
| FROM student_scores; |
| ``` |
| |
| ```text |
| +----------+-------+---------+ |
| | name | score | quarter | |
| +----------+-------+---------+ |
| | Alice | 98 | 1 | -- Top 25% scores |
| | Bob | 95 | 1 | |
| | Charlie | 90 | 2 | -- 25-50% scores |
| | David | 85 | 2 | |
| | Eve | 82 | 3 | -- 50-75% scores |
| | Frank | 78 | 3 | |
| | Grace | 75 | 4 | -- Bottom 25% scores |
| | Henry | 70 | 4 | |
| +----------+-------+---------+ |
| ``` |