DECLARE @hyphen VARCHAR(100) = '2,10',

@inputstring VARCHAR(max) = 'ABCDEFGHIJKLMNOPQRST',

@hyphen_count INT,

@i INT=1,

@key INT;

SET @hyphen_count = LEN(@hyphen) - ( LEN(REPLACE(@hyphen, ',', '')) ) + 1

WHILE @i <= @hyphen_count

BEGIN

IF ( CHARINDEX(',', @hyphen, 1) ) <> 0

SET @key = SUBSTRING(@hyphen, 1, CHARINDEX(',', @hyphen, 1) - 1)

ELSE

SET @key = @hyphen

SET @inputstring = STUFF(@inputstring, @key + @i, 1, '-')

SET @hyphen= SUBSTRING(@hyphen, @key + 1, LEN(@hyphen))

SET @i=@i + 1

END

SELECT @inputstring