Question

我显然是通过在数据库中创建表的类来使用LINQ插入数据，但是它只是显示对象为null的错误。

这是我使用C＃LINQ的示例代码：

using (dc = new linqDBDataContext(conn))
{
    Subject_Curriculum sc;
    Subject_Schedule ss;
    Subject_Department sd;
    Subject_Standing sst;

    Pre_Requisite pr;
    Pre_Requisite_Year_Standing prys;

    Curriculum cu = new Curriculum();
    cu.Curriculum_Title = curriculumName;
    cu.Course_Number = courseNumber;

    foreach (var s in ssd)
    {
        sc = new Subject_Curriculum();
        sc.Course_Code = s.courseCode;
        sc.Course_Title = s.courseTitle;
        cu.Subject_Curriculums.Add(sc);
        dc.Subject_Curriculums.InsertOnSubmit(sc);

        for (int i = 0; i < s.numberOfSchedules; i++)
        {
            ss = new Subject_Schedule();

            if (i == 0)
            {
                ss.Units = s.unitsLec;
                ss.Schedule_Type = "Lecture";
                ss.Number_Of_Hours = s.numberOfHoursLec;
            }
            else
            {
                ss.Units = s.unitsLab;
                ss.Schedule_Type = "Laboratory";
                ss.Number_Of_Hours = s.numberOfHoursLab;
            }

            sc.Subject_Schedules.Add(ss);
            dc.Subject_Schedules.InsertOnSubmit(ss);
        }

        foreach (var sdl in s.department)
        {
            sd = new Subject_Department();
            sd.Department_Number = sdl;
            sc.Subject_Departments.Add(sd);
            dc.Subject_Departments.InsertOnSubmit(sd);
        }

        sst = new Subject_Standing();
        sst.Year = s.year;
        sst.Semester = s.semester;

        cu.Subject_Standings.Add(sst);
        dc.Subject_Standings.InsertOnSubmit(sst);

        if (s.yearStandingStatus)
        {
            prys = new Pre_Requisite_Year_Standing();
            prys.Year_Standing = Convert.ToInt32(s.yearStanding.ToString().Substring(0, 1));
            sc.Pre_Requisite_Year_Standings.Add(prys);
            dc.Pre_Requisite_Year_Standings.InsertOnSubmit(prys);
        }
        else
        {
            if (s.prereq.Count == 0)
            {
                pr = new Pre_Requisite();
                pr.Pre_Requisite_Code = null;
                sc.Pre_Requisites.Add(pr);
                dc.Pre_Requisites.InsertOnSubmit(pr);
            }
            else
            {
                foreach (var p in s.prereq)
                {
                    pr = new Pre_Requisite();
                    pr.Pre_Requisite_Code = Convert.ToInt32(p);
                    sc.Pre_Requisites.Add(pr);
                    dc.Pre_Requisites.InsertOnSubmit(pr);
                }
            }
        }
    }

    dc.Curriculums.InsertOnSubmit(cu);
    dc.SubmitChanges();

    return true;
}

如代码中所示，Curriculum表在数据库中具有最高的层次结构，其他表将其主键继承到Subject_Curriculum，Pre_Requisite，Subject_Standing和Pre_Requisite_Year_Standing中。而Subject_Schedules和Subject_Department继承Subject_Curriculum的主键。我该怎么做才能一次插入所有表？

Answer 1

我已经解决了我的问题。只需通过外键添加所有表，然后在循环末尾插入并提交更改。这将使该线程关闭。

如何使用外键在LINQ中插入两个以上的表

1 个答案: