.NET (Core and Framework)

Dim dt As New DataTable()
dt.Columns.Add("Name")
dt.Columns.Add("Count")
Dim manpower1 As Integer
Dim present1 As Integer
For Each row As DataGridViewRow In manpower.Rows
    dt.Rows.Add(row.Cells(1).Value)
Next
For Each row1 As DataGridViewRow In present.Rows
    present1 = (row1.Cells(1).Value)
    dt.Rows.Add(manpower1 - present1)
Next
For Each row2 As DataGridViewRow In manpower.Rows
    dt.Rows.Add(manpower1 - present1)
Next
absent.DataSource = dt

try
                {
                    using (MemoryStream ms = new MemoryStream(fileData))
                    {                        
                        List<string> dangerous_files = new List<string>();
                        string msgModel = "ZIP: {zip} - ({file})";
                        using (ZipArchive archive = new ZipArchive(ms))
                        {
                            foreach (var entity in archive.Entries)
                            {
                                if (denyExtensions.Contains(entity.FullName.Split('.').LastOrDefault().ToLower()))
                                {
                                    dangerous_files.Add(msgModel.Replace("{zip}", GetRidOfSlash(file.FileName)).Replace("{file}", entity.FullName));
                                }
                            }
                            if (dangerous_files.Count > 0)
                            {
                                Response.TrySkipIisCustomErrors = true; Response.StatusCode = 500;
                                return Json(new
                                {
                                    error = errMsg,
                                    code = "500.1",
                                    files = dangerous_files
                                });
                            }
                        }
                    }
                }
                catch (Exception ex)
                {
                    LogHandler.LogError(4203, "Zip file creation failed Upload - Picture", ex);
                    throw ex;
                }

using (ZipArchive archive = new ZipArchive(ms))

List<TableC> cs = (from a in tablea.TableBs select a.TableCs.ToList());

The operation failed: The relationship could not be changed because one or more of the foreign-key properties is non-nullable. When a change is made to a relationship, the related foreign-key 
property is set to a null value. If the foreign-key does not support null values, a new relationship 
must be defined, the foreign-key property must be assigned another non-null value or the unrelated 
object must be deleted.

public bool Delete(NOV nov, bool performCommit = true)
{
    System.Data.Entity.DbContextTransaction dbOperation = null;
    if (performCommit)
        dbOperation = UnitOfWork.BeginTransaction();
    try
    {
        //deleting all OneToMany references to NOV
        List<ViolationTypeNOV> novRels = UnitOfWork.ViolationTypeNOVRepository
            .GetAll().Where(x => x.NOVId == nov.NOVId).ToList();

        foreach (ViolationTypeNOV o in novRels)
        {
            nov.ViolationTypeNOVs.Remove(o);
            this.UnitOfWork.ViolationTypeNOVRepository.Delete(o.ViolationTypeNOVId);
        }
        novRels.RemoveAll(x => x.NOVId == nov.NOVId);

        List<ViolationNOV> violationNOVs = UnitOfWork.ViolationNOVRepository
            .GetAll().Where(x => x.NOVId == nov.NOVId).ToList();
        foreach (ViolationNOV o in violationNOVs)
        {
            nov.ViolationNOVs.Remove(o);
            this.UnitOfWork.ViolationNOVRepository.Delete(o.ViolationNOVId);
        }
        violationNOVs.RemoveAll(x => x.NOVId == nov.NOVId);

        List<CaseNOV> caseNOVs = UnitOfWork.CaseNOVRepository
            .GetAll().Where(x => x.NOVId == nov.NOVId).ToList();
        foreach (CaseNOV o in caseNOVs)
        {
            nov.CaseNOVs.Remove(o);
            this.UnitOfWork.CaseNOVRepository.Delete(o.CaseNOVId);
        }
        caseNOVs.RemoveAll(x => x.NOVId == nov.NOVId);

        UnitOfWork.NOVRepository.Delete(nov.NOVId);

        if (dbOperation != null)
            dbOperation.Commit();

        LogHandler.LogInfo(2521, "Deleted NOV " + nov.NOVNumber);
        return true;
    }
    catch (Exception ex)
    {
        LogHandler.LogError(2523, "Commit Fail in NOV Delete", ex);
        if (dbOperation != null)
            dbOperation.Rollback();
        throw ex;
    }
}