问如何忽略继承中的鉴别列

EN

[Table("WORKFLOW_ITEM")]
public class WORKFLOW_ITEM
{
    public WORKFLOW_ITEM()
    {
        PROJECT = new HashSet<PROJECT>();
        WORKFLOW_HISTORY = new HashSet<WORKFLOW_HISTORY>();
    }

    [Key]
    public long ID_WORKFLOW_ITEM { get; set; }

    public long ID_WORKFLOW { get; set; }

    public virtual WORKFLOW WORKFLOW { get; set; }

    public virtual ICollection<WORKFLOW_HISTORY> WORKFLOW_HISTORY { get; set; }
    public virtual ICollection<PROJECT> PROJECT { get; set; }
}

[Table("WORKFLOW_ITEM")]
public class WORKFLOW_ITEMCUSTOM : WORKFLOW_ITEM
{
    public WORKFLOW_ITEMCUSTOM() 
    {
        ENGINEERING_REQUEST = new HashSet<ENGINEERING_REQUEST>();
    }

    public virtual ICollection<ENGINEERING_REQUEST> ENGINEERING_REQUEST { get; set; }
}

public class ENGINEERING_REQUEST
{
    [Key]
    public long ID_ENGINEERING_REQUEST { get; set; }

    public long? ID_WORKFLOW_ITEM { get; set; }
    public virtual WORKFLOW_ITEMCUSTOM WORKFLOW_ITEM { get; set; }
}

public class ContextCUSTOM: MyContext
{
    public ContextCUSTOM(string p_ConnectionString) :
        base(p_ConnectionString) { }

    public virtual DbSet<ENGINEERING_REQUEST> ENGINEERING_REQUEST { get; set; }
    public virtual DbSet<WORKFLOW_ITEMCUSTOM> WORKFLOW_ITEMCUSTOM{ get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        modelBuilder.Entity<ENGINEERING_REQUEST>()
            .HasOne(ct => ct.WORKFLOW_ITEM)
            .WithMany(ct => ct.ENGINEERING_REQUEST)
            .HasForeignKey(ct => ct.ID_WORKFLOW_ITEM)
            .OnDelete(DeleteBehavior.Restrict);
    }
}