DECLARE @cnt INT                       SET @cnt = 0
DECLARE @H_comment NVARCHAR(MAX)       SET @H_comment = 'This is a comment more than 50 characters long. This will be split into sets of 50 characters. There is no reason to do this in SQL, not is this a good implementation of such a way to do so. Also @cnt is declared but never used.'
DECLARE @h_len1 INT                    SET @h_len1 = LEN(@H_comment)
DECLARE @x INT                         SET @x = 1
DECLARE @doIt FLOAT                    SET @doIt = @h_len1 % 50
DECLARE @loopIt FLOAT                  SET @loopIt = @doIt

DECLARE @S_comment NVARCHAR(50)        SET @S_comment = NULL

SET @doIt = @h_len1 % 50

IF @doIt > 0 SET @loopIt = @loopIt + 1

WHILE @loopIt > 0 BEGIN

	SET @S_comment = SUBSTRING(@H_comment, @x, 50)	

	IF @S_comment > '' BEGIN
		SET @cnt = @cnt + 1
		-- Do write_comment here (this could be a proc)
		PRINT @S_comment
	END

	SET @loopIt = @loopIt - 1
	SET @x = @x + 50
END

This is a comment more than 50 characters long. Th
is will be split into sets of 50 characters. There
 is no reason to do this in SQL, not is this a goo
d implementation of such a way to do so. Also @cnt
 is declared but never used.

DECLARE @H_comment NVARCHAR(4000)

SET	@H_comment = 'This is a comment more than 50 characters long. This will be split into sets of 50 characters. There is no reason to do this in SQL, not is this a good implementation of such a way to do so. Also @cnt is declared but never used.'

SELECT	@H_comment,
	1 + number,
	SUBSTRING(@H_comment, 1 + 50 * Number, 50)
FROM	master..spt_values
WHERE	Type = 'P'
	AND LEN(@H_comment) / 50 >= Number