title: How do you insert to a SqlServer table with Ecto?
body: <p>I'm trying to hook Ecto up to an existing SqlServer database. SqlServer wants to auto-fill the primary key field, so I can't supply a value when I do an insert. I had originally marked the field as required, but even after I removed that, the INSERT query it constructs still has that field and is trying to put :nil into it. So I'm still getting an error. Is there a particular way I'm supposed to set up the model, or something I'm supposed to pass to the INSERT to make it work? How do you insert to SqlServer?</p>
  
  <p>I'm using the tds_ecto adapter. The error I get is:</p>
  
  <pre><code>Cannot insert explicit value for identity column in table 'TextMessageHistory' when IDENTITY_INSERT is set to OFF
  </code></pre>