C# 如何在linq条件下匹配列表值？

如何在linq条件下匹配列表值

我有一个ID列表，所以这些ID必须在条件上匹配，并从一个表中获取数据

public ActionResult StudentSelect(
    long? CompanyId,
    long? CompanyLocationId,
    long? ClassId,
    long? SectionId,
    long? AcademicId,
    long? ExamId) //) //long? SectionId)

下面是学生注册ID的列表

{
    var RegId = (
        from a in db.Student_Marks_Percentage
        where a.Delete_Flag == false &&
            a.Exam_Id == ExamId &&
            a.Academic_Year_Id == AcademicId &&
            a.Class_Id == ClassId
        select a.Registration_Id)
        .ToList();

    List<StudentList> Student = new List<StudentList>();

    if (AcademicId != null &&
        CompanyId != null &&
        CompanyLocationId != null &&
        ClassId == null &&
        SectionId == null) //&& )//&& ClassId != null) //)
    {
        Student = (
            from a in db.Student_Re_Admission
            join b in db.Student_Registration on a.Registration_Id equals b.Registration_Id
            join c in db.Student_Roll_No_Assign on a.Registration_Id equals c.Registration_Id
            where c.Academic_Year_Id == AcademicId &&
                c.Company_ID == CompanyId &&
                c.COMPANY_LOCATION_ID == CompanyLocationId &&
                a.Academic_Year_Id == AcademicId &&
                c.Class_Id == ClassId &&
                a.Class_Id == ClassId &&
                a.Section_Id == SectionId &&
                c.Section_Id == SectionId &&

我试着像下面一样，但得到了相同的学生名单数据

var merged = new List<StudentList>(Student);
                merged.Except(Student.Where(p2 => RegId.Exists(p1 => p2.Registration_Id != p1.Registration_Id)));

var合并=新列表（学生）；
合并。除了（Student.Where（p2=>RegId.Exists（p1=>p2.Registration\u Id！=p1.Registration\u Id））；

我想您只需要更换

a.Registration\u Id！=RegIds

带有：

!RegIDs.Contains(a.Registration_Id)

---

我想你只需要更换

a.Registration\u Id！=RegIds

带有：

!RegIDs.Contains(a.Registration_Id)

---

第一个必须进行比较的变量列表

var RegId = (from a in db.Student_Marks_Percentage
                         where a.Delete_Flag == false
                         && a.Exam_Id == ExamId
                        && a.Academic_Year_Id == AcademicId
                        && a.Class_Id == ClassId
                         select a).ToList();

必须获取数据的第二个列表

List<StudentList> Student = new List<StudentList>();

            if (AcademicId != null && CompanyId != null && CompanyLocationId != null && ClassId == null && SectionId == null) //&& )//&& ClassId != null) //)
            {
                Student = (from a in db.Student_Re_Admission
                           join b in db.Student_Registration on a.Registration_Id equals b.Registration_Id
                           join c in db.Student_Roll_No_Assign on a.Registration_Id equals c.Registration_Id                           

                           where c.Academic_Year_Id == AcademicId && c.Company_ID == CompanyId && c.COMPANY_LOCATION_ID == CompanyLocationId
                           && a.Academic_Year_Id == AcademicId && c.Class_Id == ClassId && a.Class_Id == ClassId
                           && a.Section_Id == SectionId && c.Section_Id == SectionId
                           //&& a.Registration_Id != RegId.Contains(a.Registration_Id)
                           && a.Promoted == false && a.Delete_Flag == false
                           //a.Academic_Year_Id == AcademicId && a.Company_ID == CompanyId && a.COMPANY_LOCATION_ID == CompanyLocationId

                           select new StudentList()
                           {
                               Registration_Id = a.Registration_Id,
                               Admission_No = a.Admission_No,
                               Student_First_Name = a.Student_First_Name,
                               Student_Middle_Name = a.Student_Middle_Name,
                               Student_Last_Name = a.Student_Last_Name,
                               Set_Roll_No = c.Set_Roll_No,
                               Roll_Id = c.Roll_Id

                           }).OrderBy(a => a.Registration_Id).ToList();
}

---

第一个必须进行比较的变量列表

var RegId = (from a in db.Student_Marks_Percentage
                         where a.Delete_Flag == false
                         && a.Exam_Id == ExamId
                        && a.Academic_Year_Id == AcademicId
                        && a.Class_Id == ClassId
                         select a).ToList();

必须获取数据的第二个列表

List<StudentList> Student = new List<StudentList>();

            if (AcademicId != null && CompanyId != null && CompanyLocationId != null && ClassId == null && SectionId == null) //&& )//&& ClassId != null) //)
            {
                Student = (from a in db.Student_Re_Admission
                           join b in db.Student_Registration on a.Registration_Id equals b.Registration_Id
                           join c in db.Student_Roll_No_Assign on a.Registration_Id equals c.Registration_Id                           

                           where c.Academic_Year_Id == AcademicId && c.Company_ID == CompanyId && c.COMPANY_LOCATION_ID == CompanyLocationId
                           && a.Academic_Year_Id == AcademicId && c.Class_Id == ClassId && a.Class_Id == ClassId
                           && a.Section_Id == SectionId && c.Section_Id == SectionId
                           //&& a.Registration_Id != RegId.Contains(a.Registration_Id)
                           && a.Promoted == false && a.Delete_Flag == false
                           //a.Academic_Year_Id == AcademicId && a.Company_ID == CompanyId && a.COMPANY_LOCATION_ID == CompanyLocationId

                           select new StudentList()
                           {
                               Registration_Id = a.Registration_Id,
                               Admission_No = a.Admission_No,
                               Student_First_Name = a.Student_First_Name,
                               Student_Middle_Name = a.Student_Middle_Name,
                               Student_Last_Name = a.Student_Last_Name,
                               Set_Roll_No = c.Set_Roll_No,
                               Roll_Id = c.Roll_Id

                           }).OrderBy(a => a.Registration_Id).ToList();
}

---

你能解释一下结果是什么吗。您所说的id列表有点不清楚是第一个（Reg）查询的结果还是where子句中唯一的id？我想要一个结果：获取不应包含var RegId listsplz注册id的数据现在查看我更新的上一个。您能解释一下除了结果之外还有什么吗。您提到的id列表有点不清楚是第一个（Reg）查询的结果还是where子句中的唯一id？我想要一个结果：获取不应包含var RegId listsplz的RegistrationId的数据现在查看我更新的最后一个。in contains（Registration_id）什么是“Registration_id”？抱歉，我忘了

a.

部分。现在有意义吗？获取编译时错误：错误227“System.Collections.Generic.List.Contains（Model.Student\u Marks\u Percentage）”的最佳重载方法匹配项包含一些无效参数（Registration\u Id）“Registration\u Id”是什么？抱歉，我忘记了

a.

部分。现在有意义了吗？获取编译时错误：错误227“System.Collections.Generic.List.Contains（Model.Student\u Marks\u Percentage）”的最佳重载方法匹配具有一些无效参数