title: take query from sql by LINQ
body: <p>Pardon my English, I'm not a native speaker.</p>
  
  <p>I want to take a query from <code>SQL</code> by linq, but in one of the reference table's data has saved null, when zero query will come back</p>
  
  <pre><code>LinqShoppingDataContext linqedit = new LinqShoppingDataContext();
  
  var j = (from a in linqedit.Kharids
           join k in linqedit.KalaNames on a.KalaName_ref equals k.ID
           join n in linqedit.KindOfKharids on a.KindOfKharid_ref equals n.ID
           join g in linqedit.VahedeKharids on a.Vahedekharid_ref equals g.ID
           select new
           {
               a.ID,
               نام_کالا = k.Name,
               مقدار = a.mount.Value,
               واحد_خرید = g.Name,
               قیمت = a.Price,
               نوع_خرید = n.Name,
               نام_خریدار = a.NameKHaridar,
               تاریخ = a.Date.Date.Year + "/" + a.Date.Date.Month + "/" + a.Date.Date.Day
           }).ToList();
  
  dataGridView1.DataSource = j;
  </code></pre>
  
  <p>This is my query but the data has saved in <code>KindOfKharids</code> table is null, so the query come back zero answer, how do I resolve my problem?</p>