The SQL Server ATAN function is a Mathematical Function that calculates the trigonometry Arc tangent for the specified expression. The SQL Arc tangent is also called the inverse of a TANGENT Function.
The syntax of the SQL ATAN Function is
SELECT ATAN (Float_Expression) FROM [Source]
For this demo, we use the below shown Math Table data

SQL ATAN Function Example
It calculates the Arctangent value for the given angle. The following query shows multiple ways to use the ATAN function.
We used the Mathematical Function to calculate the Arc TANGENT value for the variable @i. It means ATAN(-208.80)) and assigned a new name, ‘Arc Tangent’ using ALIAS.
DECLARE @i Float SET @i = -208.80 SELECT ATAN(@i) AS [Arc Tangent] -- Calculating ATAN directly SELECT ATAN(0.27) AS [Arc Tangent] -- Calculating ATAN directly SELECT ATAN(22.25 + 78.55 - 140.77) AS [Arc Tangent]

ATAN Function Example 2
We are going to calculate the Arctangent value for all the records present in [Service Grade] using this SQL Serve Function
SELECT [EnglishProductName] ,[Color] ,[StandardCost] ,[SalesAmount] ,[Service Grade] AS Grade ,ATAN([Service Grade]) AS [Arc Tangent] FROM [Mathemetical Functions]
