how to use stddev (standard deviation) function in oracle plsql

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.

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SQL Standard Deviation Function Syntax

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

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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.

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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.

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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.

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