In this tutorial, we will study the MySQL **Cume_Dist()** function which is used to calculate the cumulative distribution value.

*Also read: MySQL Nth_Value Function – A Complete Reference*

## Introduction

**Cume_Dist()** function is a window function that is used to calculate the cumulative distribution value among a set of values. Here the Row number less than or equal to the row’s value is divided by the total number of rows. The formula is **ROW_NUMBER () / total_rows**.

The **Cume_Dist()** function calculates the cumulative distribution value of each row based on its order in the partition.

### Syntax of MySQL CUME_DIST()

Code language: SQL (Structured Query Language) (sql)`CUME_DIST() OVER ( PARTITION BY expr, ... ORDER BY expr [ASC | DESC], ... )`

The value returned by **Cume_Dist()** function is greater than 0 and less than or equal to 1. **Partition By **clause is used to divide the result set and **Order By** is used to specify the order of the rows in the result set.

## Example of MySQL Cume_Dist()

First, we will create a table named **detail** and insert some data into it. The code for this is-

```
Create Table detail (
name Varchar(20) Primary Key,
value Int Not Null
);
Insert into
detail (name, value)
values
('Peter', 45),
('David', 98),
('John' , 67),
('Lily', 88),
('Lisa', 33),
('William', 100),
('Chuck', 93),
('Taylor', 55);
```

Code language: SQL (Structured Query Language) (sql)

Now we will find the cumulative distribution of value in the result set. The code for this is-

```
Select
name,
value,
ROW_NUMBER() OVER (ORDER BY score) row_num,
CUME_DIST() OVER (ORDER BY score) cume_dist_val
FROM
detail;
```

Code language: SQL (Structured Query Language) (sql)

**Output-**

**Working** **of Cume_Dist() Function**

In the first row, the function first finds the number of rows in the result set which has a value less than or equal to 33 and such rows is only 1. Then `CUME_DIST()`

function divides 1 by the total number of rows which is 8. 1/8 is 0.125. The same logic is applied to the second row, third row, and so on.

In this way, **Cume_Dist() ** function finds the cumulative distribution of each row in the result set.

## Conclusion

In this tutorial, we studied MySQL Cume_Dist() window function which helps us to find the cumulative distribution of each row in the result set. For more reference, check the official documentation of MySQL.