MySQL does not support NTILE functions, but can be implemented through variable simulation. 1. NTILE(n) is a window function that sorts data equally and divides n groups and assigns group numbers; 2. MySQL 8.0 still does not support NTILE, and needs to be simulated manually: sort first, calculate the total number of rows, and divide groups with row numbers; 3. Practical applications such as sales rating and grade grading; 4. Notes include ensuring data sorting, clarifying the number of groups, and processing boundary values.
MySQL's NTILE
function is actually not a function natively supported by MySQL, but a window function that is more common in databases such as PostgreSQL and SQL Server. If you encounter the keyword "NTILE" when using MySQL, you usually want to implement similar functions, such as dividing data into groups or buckets.

Here are some practical usages and alternatives you may be concerned about.
What is an NTILE function?
NTILE(n)
is a window function. Its function is to divide the result set into n groups evenly according to the specified sorting method, and assign a group number (from 1 to n) to each row. If the score cannot be completely evenly divided, the previous group will have one more row.

For example:
name | score |
---|---|
Alice | 95 |
Bob | 90 |
Carol | 85 |
Dave | 80 |
Eve | 75 |
If we use NTILE(2)
to group by score, the first two rows will be divided into group 1 and the last three rows will be divided into group 2 (or, in turn, depending on the specific implementation details).

How to implement NTILE function in MySQL?
MySQL did not support window functions before version 8.0, including NTILE
. But starting with MySQL 8.0, it has started to support some window functions, but it still does not support NTILE()
. So you need to simulate manually.
Method 1: Use variables to simulate NTILE
The basic idea is to sort the data first, then calculate the total number of rows, and then divide the groups according to the row number.
For example, we want to divide students into 4 groups by grade:
SELECT name, score, CEIL(row_num / (total_rows / 4)) AS group_id FROM ( SELECT name, score, @row := @row 1 AS row_num, (SELECT COUNT(*) FROM students) AS total_rows FROM students, (SELECT @row := 0) r ORDER BY score DESC ) AS ranking;
illustrate:
-
@row
is an autoincrement variable used to generate line numbers. -
total_rows
calculates the total number of people. -
CEIL(row_num / (total_rows / 4))
maps line numbers to group numbers from 1 to 4.
Note: When this method is not a multiple of 4, the first few groups may have one more row.
Examples of practical application scenarios
Scenario 1: Sales Performance Ranking Group
You want to divide sales personnel into four levels based on sales from high to low, so as to facilitate performance evaluation.
You can sort by sales first and then assign group numbers using the above method. This way, the number of people in each group is roughly equal, which is suitable for sampling analysis or rating.
Scene 2: Exam score grading
The school wants to grade students A/B/C/D, and try to average the number of students at each level. This is also possible to use similar simulation methods to achieve this.
Notes on using NTILE alternatives
- Data must be sorted : NTILE is grouped based on ordered data, so you must clearly sort the fields before use.
- It is best to determine the number of groups in advance : for example, if you want to divide into 4 groups or 5 groups, this will affect the final grouping logic.
- When data distribution is uneven, pay attention to processing boundary values : for example, if there are duplicate sorting field values, should they be classified into the same group? This requires additional judgment.
Summarize
Although MySQL does not directly support the NTILE()
function at present, we can simulate similar effects by adding mathematical operations to variables. Although this method is a little more complex, it is very practical in actual projects, especially in scenarios such as data analysis, ranking grouping, and level division.
Basically all this is it. The key is to understand the grouping logic and flexibly adjust it in combination with specific business needs.
The above is the detailed content of mysql ntile function. For more information, please follow other related articles on the PHP Chinese website!

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