title: Error while adding multiple items to an entity
body: <pre><code>for (int i = 0; i &lt; skus.Count; i++)
  {
      sku item = new sku();
      item = skus[i];
      sku sku = CompanyDbContext.skus.Where(s =&gt; s.item_no == item.item_no).FirstOrDefault();
  
      if (sku == null) // ok to insert [no duplicate item numbers]
      {
          CompanyDbContext.skus.Add(item);                             
      }
  
  }
  CompanyDbContext.SaveChanges();
  </code></pre>
  
  <p>I'm getting </p>
  
  <blockquote>
    <p>collection was modified enumeration operation may not execute</p>
  </blockquote>
  
  <p>error. How can I fix this ?</p>