如何用未来和当前日期验证存在

Question

我有身体检查的模型

public class PatientMedicalExam
{
    public int Id {get; set;}
    public int PatientId {get; set;}
    public int MedicalExamId {get; set;}
    public DateTime Date {get; set;} // realization date
    public DateTime NextDate {get; set;}
}

无论何时添加考试，考试都会有下一个日期（NextDate） 我想根据输入的日期（NextDate）返回下一次检查，如果已经存在（Date），则该检查不存在

我尝试过：

   var query = db.PatientMedicalExams.AsQueryable()
                .Where(x =>
                     x.NextDate != null &&
                     DbFunctions.TruncateTime(x.NextDate) >= model.Start &&
                     DbFunctions.TruncateTime(x.NextDate) <= model.End &&
                     DbFunctions.TruncateTime(x.Date) <= model.End &&
                     DbFunctions.TruncateTime(x.Date) >= model.End);

[编辑]样本数据

Start参数= 01/01/2019 End参数= 31/01/2019

ID, PATIENTID, MEDICALEXAMID,    DATE,       NEXTDATE
1      1             1        01/01/2018    01/01/2019   //this next date for medical examination
2      1             2        01/01/2018    01/01/2019   //expired
3      1             1        12/31/2018    12/31/2019  //this medical examination has been realized before expiration 

然后patientid 1到期的唯一医学检查是medicalexamId 2