# STDDEV, STDEV – Return standard deviation of selected column – Aggregate Functions

STDDEV or STDEV function return the standard deviation of selected column.

Standard deviation tells how much dispersion there is from an average value. Small standard deviation tells the each value is close to the average value. Large standard deviation indicates that the each value is spread out from average value.

example: Return the standard deviation of employees’ salary.

SELECT STDDEV(salary) FROM tbSalaryTable; STDDEV(salary) -------------------------------- 8.25394

Oracle uses STDDEV, and SQL Server uses STDEV.

Posted in Aggregate Functions