In the last tutorial we left off with the SUM(column) function. In this article we will cover the remaining Aggregate Functions and the Scalar Functions. We might even make some fat jokes, some mama jokes, and as always, some nerd jokes.
When you are dealing with a huge amount of data, STDEV can return the Standard Deviation of a column. You have to have a minimum of two values or the value returned will be null.
Here is how it looks in code:
Select STDEV(Salary) As SDSalary
From Employees
The above function takes a sampling of your data instead of the whole list, and returns the standard deviation.
STDEVP
If you want to work with all the data in a column to find the standard deviation, you can use STDEVP instead.
Select STDEVP(Salary) As DevSalary
From Employees
VAR
The VAR Function allows you to find the variance of a set of data from a column. Like STDEV, VAR only works with a sampling and not the whole column. And again, you must have at least two values in the column or a null will be returned.
Select VAR(Salary) As VARSalary
From Employees
VARP
To get a variance using all of the data in a column, use this handy little guy.
