Asp.net MVC проверьте, является ли эта регистрация бесплатной или нет

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Я новичок в этом деле asp.net mvc.Pleace помогите мне проверить, существует ли значение, которое я написал в своей базе данных.значение 4columns должно проверить и вернуть сообщение

Что я уже пробовал:

namespace poezd.Models
{
    using System;
    using System.Collections.Generic;
    
    public partial class Reqistration
    {
        public int ID { get; set; }
        public string CustomerName { get; set; }
        public Nullable<int> PoezdID { get; set; }
        public Nullable<int> VaqonID { get; set; }
        public Nullable<int> MestoID { get; set; }
        public Nullable<System.DateTime> Date { get; set; }
    
        public virtual Poezd Poezd { get; set; }
        public virtual MestoVaqon MestoVaqon { get; set; }
        public virtual Vaqon Vaqon { get; set; }
    }
}

мой класс reqistration(проверить, если VaqonID &амп;&амп; PoezdID &амп;&амп; MestoID &&усилителя; дата)уже существует.

@using (Html.BeginForm()) 
{
    @Html.AntiForgeryToken()
    
    <div class="form-horizontal">
        <h4>Reqistration</h4>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        <div class="form-group">
            @Html.LabelFor(model => model.CustomerName, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.CustomerName, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.CustomerName, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.PoezdID, "PoezdID", htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.DropDownList("PoezdID", null, htmlAttributes: new { @class = "form-control" })
                @Html.ValidationMessageFor(model => model.PoezdID, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.VaqonID, "VaqonID", htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.DropDownList("VaqonID", null, htmlAttributes: new { @class = "form-control" })
                @Html.ValidationMessageFor(model => model.VaqonID, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.MestoID, "MestoID", htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.DropDownList("MestoID", null, htmlAttributes: new { @class = "form-control" })
                @Html.ValidationMessageFor(model => model.MestoID, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.Date, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Date, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Date, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                @Html.
                <input type="submit" value="Create" class="btn btn-default" />
            </div>
        </div>
    </div>
}

[HttpPost]
       [ValidateAntiForgeryToken]
       public ActionResult Create([Bind(Include = "ID,CustomerName,PoezdID,VaqonID,MestoID,Tarix")] Reqistration reqistration)
       {
           if (ModelState.IsValid )
           {
               db.Reqistration.Add(reqistration);
               db.SaveChanges();
               return RedirectToAction("Index");
           }


           ViewBag.PoezdID = new SelectList(db.Poezd, "ID", "Name", reqistration.PoezdID);
           ViewBag.MestoID = new SelectList(db.MestoVaqon, "ID", "ID", reqistration.MestoID);
           ViewBag.VaqonID = new SelectList(db.Vaqon, "ID", "Vaqon1", reqistration.VaqonID);
           return View(reqistration);
       }

это registrationsController

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