title: update-database not working in Code first
body: <p>I am using entity  framework and Codefirst to create a Stored procedure. 
  As I reed, we should do some steps in package manager to create SP. </p>
  
  <p>1 - enable migration</p>
  
  <p>2- add-migration MYclass</p>
  
  <p>3- update-database</p>
  
  <p>and in <code>Myclass(new created)</code> I write my SP code in UP() method to create SP. works fine!! BUT when I change SP and run update-database again it does not work and I need to do another add-migration command to create new MYclass2. Is that right? I mean every time I should write add-migration? </p>
  
  <p>this is mycode</p>
  
  <pre><code>  public override void Up()
          {
              Sql(@"Create procedure testSp 
                          as 
  select std.Id as stdName, std.Name as MajorName, mj.Name from dbo.Students as std
  inner join dbo.Majors as mj on std.Id = mj.Id
  ");
          }
  
          public override void Down()
          {
              Sql("drop procedure testSp");
          }
  </code></pre>
  
  <p>when I run update-database again the result is <code>"No pending explicit migration"</code></p>
  
  <p>even if I change the SQL query to "Alter procedure...." it does not work , no change happens.
  thanks</p>
  
  <p><strong><em>EDITED</em></strong></p>
  
  <p>consider this scenario, I want to change my SP name(just an example)
  so I need to change the query to "Alter store procedure tespSP2 ..." 
  or any other change, should I run add-migration again?? or update-database is supposed to do it??</p>