DECLARE @cols   AS NVARCHAR(MAX),
		@query  AS NVARCHAR(MAX),
		@date varchar(10)
set		@date = 201805

SET @cols = STUFF((SELECT
		',' + QUOTENAME(CAST(product_id AS VARCHAR(50)))
	from dbo.sales
	GROUP BY product_id
	ORDER BY product_id
	FOR XML PATH (''), TYPE).value ('.', 'NVARCHAR(MAX)'), 1, 1, '')

SET @query = '
			  SELECT *
			  FROM
					( select client_id, product_id, sum(sales_value) as val,cast(year(date) as varchar(10)) + ''0'' + cast(month(date) as varchar(10))	af
					  from   dbo.sales
					   group by [client_id],
							    [product_id],
							   	cast(year(date) as varchar(10)) + ''0'' + cast(month(date) as varchar(10))
					   having   cast(year(date) as varchar(10)) + ''0'' + cast(month(date) as varchar(10)) =   ' + @date + '
					       and  sum([sales_value]) > 500000
					) x
							PIVOT
								( SUM(val) for product_id in (' + @cols + ') ) p'


EXECUTE (@query)