how-to populate a table's column with values from the same table's another column using set based approach

-- UNDERSTANDIGN SET BASED APPROACH 

--set nocount off;

--select column_name from INFORMATION_SCHEMA.COLUMNS where TABLE_NAME='Products'

--Declare the Table variable 

DECLARE @tmpTable TABLE

(

Number INT IDENTITY(1,1), --Auto incrementing Identity column

CultureNameU VARCHAR(300) --The string value

)

--Decalre a variable to remember the position of the current delimiter

DECLARE @CurrentDelimiterPositionVar INT 

--Decalre a variable to remember the number of rows in the table

DECLARE @Count INT

--Populate the TABLE variable using some logic

INSERT INTO @tmpTable SELECT CultureName FROM CultureInfo

--Initialize the looper variable

SET @CurrentDelimiterPositionVar = 1

--Determine the number of rows in the Table

SELECT @Count=max(Number) from @tmpTable

--A variable to hold the currently selected value from the table

DECLARE @CurrentValue varchar(300);

--Loop through until all row processing is done

WHILE @CurrentDelimiterPositionVar <= @Count

BEGIN

--Load current value from the Table

SELECT @CurrentValue = CultureNameU FROM @tmpTable WHERE Number = @CurrentDelimiterPositionVar

--Process the current value

declare @replaced varchar(300)

set @replaced = replace(@CurrentValue , '-' , '_')

update CultureInfo set CultureNameU=@replaced where CultureName=@CurrentValue

print @replaced  

--Increment loop counter

SET @CurrentDelimiterPositionVar = @CurrentDelimiterPositionVar + 1;

END