title: Manually add a migration?
body: <p>I've been using Entity framework code first in a project and all the tables have been created /modified a while ago. Now I need to add an unique constraint to a table. I want to create a migration which will have the following row in the <code>Up()</code> method. And there is <strong>no change on the model classes</strong>. </p>
  
  <pre><code>CreateIndex("TableName", new[] { "Column1" }, true, "IX_UniqueKey");
  </code></pre>
  
  <p>And maybe the following row in the <code>Down()</code></p>
  
  <pre><code>DropIndex("TableName", new [] { "Column1" });
  </code></pre>
  
  <p>Can I just manually create a file under the folder <em>Migrations</em>? And is there any mandatory file name convention? </p>
  
  <p>How to create the <code>.Designer.cs</code> and <code>.resx</code> files? Or should I use <code>add-migration</code> with some parameters? </p>