title: Add column to existing SQL Server table - Implications
body: <p>I have an existing table in SQL Server with existing entries (over 1 million in fact).  </p>
  
  <p>This table gets updated, inserted and selected from on a regular basis by a front-end application. I want/need to add a <code>datetime</code> column e.g. <code>M_DateModified</code> that can be updated like so:</p>
  
  <pre><code>UPDATE Table SET M_DateModified = GETDATE()
  </code></pre>
  
  <p>whenever a button gets pressed on the front-end and a stored procedure gets called. This column will be added to an existing report as requested.</p>
  
  <p>My problem, and answer is this. Being one of the core tables of our app, will <code>ALTERING</code> the table and adding an additional column break other existing queries? Obviously, you can't insert into a table without specifying all values for all columns so any existing <code>INSERT</code> queries will break (WHICH is a massive problem).</p>
  
  <p>Any help would be much appreciated on the best solution regarding this problem. </p>