SQL STDDEV/Standard Deviation Function

SQL Standard Deviation or SQL STDDEV Function returns the standard deviation of available records. Oracle Standard Deviation or Oracle STDDEV Function can accept a column name or formula as parameter for Standard Deviation calculation.

SQL Standard Deviation Function Syntax

SELECT STDDEV(numeric column / formula)
FROM table_name
WHERE conditions;

SQL Standard Deviation Function Examples

Suppose we have a table named “Employee” with the data as shown below.

Employee_Id	Employee_Name	Salary	Department	Commission
101	Emp A	10000	Sales	10
102	Emp B	20000	IT	20
103	Emp C	28000	IT	20
104	Emp D	30000	Support
105	Emp E	32000	Sales	10

Oracle STDDEV Function application is shown below.

SQL Standard Deviation – SQL STDDEV Simple Usage Example

SQL Standard Deviation query below will return the standard deviation of salaries of all employees.

SELECT STDDEV(salary) "SQL STDDEV"
FROM employee;

Above Oracle Standard Deviation query returns ‘9055.38513813742’ as standard deviation of all salaries in ‘employee’ table.

Note: We have aliased STDDEV(salary) as SQL STDDEV.

Oracle Standard Deviation – Oracle STDDEV Using Formula Example

SQL Standard Deviation query below calculates the Standard Deviation of Salary*Commission for ’employee’ table.

SELECT STDDEV(salary*(commission/100)) "Oracle STDDEV"
FROM employee;

Above Oracle Standard Deviation query returns ‘1913.98362932741’ as standard deviation of all salary*(commission/100) of ‘employee’ table.

Note: We have aliased STDDEV(salary*(commission/100)) as Oracle STDDEV.