title: add a getdate() default value while adding a column
body: <p>Useally if I want to add default value , I use this way</p>
  
  <pre><code>ALTER TABLE tab1 ADD  coll datetime DEFAULT '11-01-15' NOT NULL
  </code></pre>
  
  <p>however I want to add default value as the getdate().<br/>
  so If use the below I got the below error</p>
  
  <pre><code>ALTER TABLE tab1 ADD  coll datetime DEFAULT GETDATE() NOT NULL
  
  error: ALTER TABLE 'tab1' failed. Default cannot be an expression when adding non-NULL column 'tab1'. Use a default value instead.
  </code></pre>
  
  <p>what I want is the default value is the getdate(). how to do that when adding a new datetime column ? </p>