DATEDIF 功能

Created: November-22, 2018

当单位忽略年份时，要小心闰年计算。例如：

 placeholderCopy=datedif("2010-01-01","2010-07-21","YD")

返回 201 天

 placeholderCopy=datedif("2016-01-01","2016-07-21","YD")

返回 202 天