C# 如果将DateAdd函数放在SELECT和FROM以及FROM和WHERE之间，则会有不同

我创建了一个必须由datetimepicker控制的查询，我的目标是获得datetimepicker设置的指定日期的接下来7天

我在我的查询中尝试了它，但它似乎没有任何区别，或者我的查询代码就是错的

     select count(PatientID) as id, Patient.FirstName, Patient.LastName, 
      Patient.MiddleName, " +"Patient.Nickname, Patient.Age, 
       Patient.Birthday, Patient.Sex, Patient.Occupation, 
       Patient.CompleteAddress, Patient.MobilePhone, Patient.Phone, " +
       "Patient.PersonTCI, Patient.PContact, Patient.DateofC 

       from Patient 

        Where DATEADD ('d' , 7 , datetimepicker1 ) and Active = '1' " + "

        Group by Patient.FirstName, 
        Patient.LastName, Patient.MiddleName, 
        Patient.Nickname, Patient.Age, Patient.Birthday, Patient.Sex, 
        Patient.Occupation, Patient.CompleteAddress, " +
        "Patient.MobilePhone, Patient.Phone, Patient.PersonTCI, 
          Patient.PContact, Patient.DateofC"

---

where子句中缺少日期比较的条件。 这个怎么样

var dateFrompicker = datetimepicker1.AddDay(7);
select count(PatientID) as id, Patient.FirstName, Patient.LastName, 
      Patient.MiddleName, " +"Patient.Nickname, Patient.Age, 
       Patient.Birthday, Patient.Sex, Patient.Occupation, 
       Patient.CompleteAddress, Patient.MobilePhone, Patient.Phone, " +
       "Patient.PersonTCI, Patient.PContact, Patient.DateofC 

       from Patient 

        Where dateFrompicker >  Patient.DateofC   and Active = '1' " + "

        Group by Patient.FirstName, 
        Patient.LastName, Patient.MiddleName, 
        Patient.Nickname, Patient.Age, Patient.Birthday, Patient.Sex, 
        Patient.Occupation, Patient.CompleteAddress, " +
        "Patient.MobilePhone, Patient.Phone, Patient.PersonTCI, 
          Patient.PContact, Patient.DateofC"

---

您认为或期望DATEADD'd'，7，datetimepicker1和Active='1'将起到什么作用？您希望在datetime picker中获取所选日期之后的7天，还是之前的7天？您在查询中将其与哪个日期值进行比较？谢谢

    select count(PatientID) as id, Patient.FirstName, Patient.LastName, 
          Patient.MiddleName, " +"Patient.Nickname, Patient.Age, 
           Patient.Birthday, Patient.Sex, Patient.Occupation, 
           Patient.CompleteAddress, Patient.MobilePhone, Patient.Phone, " +
           "Patient.PersonTCI, Patient.PContact, Patient.DateofC 
       from Patient 

        Where Patient.DateofC>=Patient.DateofC and Patient.DateofC<= datetimepicker1.value.AddDay(7)     and Active = '1' " + "

        Group by Patient.FirstName, 
        Patient.LastName, Patient.MiddleName, 
        Patient.Nickname, Patient.Age, Patient.Birthday, Patient.Sex, 
        Patient.Occupation, Patient.CompleteAddress, " +
        "Patient.MobilePhone, Patient.Phone, Patient.PersonTCI, 
          Patient.PContact, Patient.DateofC"