SQL SQRT Function

The SQL SQRT Function finds the square root of the specified expression or numeric number. The syntax of the SQL Server SQRT Function to find the square root is

SELECT SQRT (Float_Expression)
FROM [Source]

For this Sql Server SQRT Function demo, we use the Math Table data

SQL SQRT Function Example 1

The SQRT Function finds the square root of a given numeric value. The following Mathematical Function query will show multiple ways to use the SQRT function.

DECLARE @i float = 4, @j int = 2.20

SELECT SQRT(@i) AS [SQL SQRT]

-- Calculating SQRT directly
SELECT SQRT(9.90) AS [SQL SQRT]

-- Wrong Value
SELECT SQRT(@j) AS [SQL SQRT]
SELECT SQRT(2.20) AS [SQL SQRT]
SQL SQRT FUNCTION 1

We declared a float, int variable and assigning the values.

DECLARE @i float = 4, @j int = 2.20

We used the SQL Server SQRT function to calculate the square root of the variable @i

SELECT SQRT(@i) AS [SQL SQRTI]

It means, √4 = 2. Next, we used the integer value as input for the SQRT function.

-- Wrong Value
SELECT SQRT(@j) AS [SQLSQRT]
SELECT SQRT(2.20) AS [SQL SQRT]

It means, SQRT (@j) = √2.20 = 1.483. But we are getting 1.4142 as a result because it is rounding the 2.20 value to 2 and the square root of 2 is 1.4142

NOTE: Please use float variables as an input for SQRT Function. Otherwise, you may expect strange results.

SQRT Function Example 2

The Square Root Function (SQRT) also allows you to find the square root of column values. Here, We will calculate the square of All the records present in [Sales Amount] using the SQRT Function.

SELECT [EnglishProductName]
      ,[Color]
      ,[StandardCost]
      ,[SalesAmount]
      ,SQRT([SalesAmount]) AS Sales
 FROM [Mathemetical Functions]
SQL SQRT FUNCTION 2