Standard Deviation - (MySQL Misc)
In MySQL, the standard deviation is a statistical function that calculates the standard deviation of a set of data. The standard deviation can be used to calculate the variability of a set of data from its mean. In this tutorial, we will discuss how to calculate standard deviation in MySQL.
Syntax
The syntax for calculating standard deviation in MySQL is as follows:
SELECT STDDEV(column_name) FROM table_name;
In the above syntax, "column_name" is the name of the column for which you want to calculate the standard deviation, and "table_name" is the name of the table containing the data.
Example
Suppose we have a table called "grades" containing the following data:
| id | name | grade |
|---|---|---|
| 1 | John | 80 |
| 2 | Jane | 90 |
| 3 | Peter | 85 |
| 4 | Mary | 75 |
| 5 | Alice | 95 |
To calculate the standard deviation of the grades of all students, we can use the following query:
SELECT STDDEV(grade) FROM grades;
The output of this query will be:
8.426149773176359
Explanation
In the example above, we used the "STDDEV" function to calculate the standard deviation of the "grade" column in the "grades" table. The result is 8.426149773176359, which indicates the degree of variation of the grades around the mean.
Use
The standard deviation function can be used in various applications, such as quality control, financial analysis, and scientific research.
Important Points
- The standard deviation function calculates the degree of variation of a set of data around the mean.
- A low standard deviation indicates that the data is clustered closely around the mean, while a high standard deviation indicates that the data is spread out over a wider range.
- The standard deviation function in MySQL can only be used on numerical data.
- The standard deviation function is sensitive to outliers, which can skew the result.
Summary
In this tutorial, we discussed how to calculate the standard deviation of data in MySQL by using the "STDDEV" function. The standard deviation is an important statistical function that measures the variability of a set of data from its mean. Understanding how to use the standard deviation function in MySQL can be helpful in various data analysis applications.