datediffdatediff datediff介绍 datediff(endDate, startDate) - 返回从 startDate 到 endDate 的天数差。 Examples: > SELECT datediff('2009-07-31', '2009-07-30'); 1 > SELECT datediff('2009-07-30', '2009-07-31'); -1 Since: 1.5.0dateadddatepart