Count the difference of character in two string in SQL Server

Create the sql function and use it like below :


--Select dbo.DiffCount('BOB', 'BOB')
CREATE FUNCTION dbo.DiffCount(@Str1 varchar(500), @Str2 varchar(500))
Returns int As
BEGIN
DECLARE @len1 INT,
@len2 INT,
@DiffLen INT,
@CharIndex INT,
@Inc INT,
@diffcount INT

SELECT @len1 = DATALENGTH(@str1),
@len2 = DATALENGTH(@str2),
@DiffLen = @len1 - @len2,
@diffcount = 0,
@Inc = 1

IF @len1 <= @len2 BEGIN

WHILE @Inc <= @len2 BEGIN

IF SUBSTRING(@str1,@inc,1) = NULLIF(SUBSTRING(@str2,@inc,1),' ') BEGIN
set @diffcount = @diffcount
END ELSE BEGIN
SET @diffcount = @diffcount + 1
END
SET @Inc = @Inc + 1
END
END ELSE IF @len1 > @len2 BEGIN
WHILE @Inc <= @len1 BEGIN

IF NULLIF(SUBSTRING(@str1,@inc,1),' ') = SUBSTRING(@str2,@inc,1) BEGIN
set @diffcount = @diffcount
END ELSE BEGIN
SET @diffcount = @diffcount + 1
END
SET @Inc = @Inc + 1
END

END
RETURN @diffcount
END