在sql的条件里进行日期添加或减去一个值（年月日的一个值）

DATEADD(day,-6,Duetime) <= GETDATE()

//在DataView中排序

strSql += strWhere + " ";

strSql += " and Pmn_ExecutePlanDate>getdate()";

strSql += " and getdate()< DATEADD(dd,-Pmn_PReTimeSpan,Pmn_ExecutePlanDate)";

//条件判断

DATEDIFF(datepart, startdate, enddate)

一下是diff的参数

Datepart Abbreviations

year yy, yyyy

quarter QQ, q

month mm, m

dayofyear dy, y

day dd, d

week wk, ww

hour hh

minute mi, n

second ss, s

millisecond ms