如果SQL查询中的日期为空，则显示所有记录

SET @dateFrom = ''
SET @dateTo = ''

SELECT [tNumber], [createdDate], [Total], [pfAmount] FROM [webtable]
WHERE [tNumber] LIKE '%' 
AND [createdDate] > @dateFrom+'%' 
AND [createdDate] < @dateTo+'%' 
SET @dateFrom = ''
SET @dateTo = ''

SELECT [tN