title: How can a not null constraint be dropped?
body: <p>Let's say there's a table created as follows:</p>
  
  <pre><code>create table testTable ( colA int not null )
  </code></pre>
  
  <p>How would you drop the not null constraint? I'm looking for something along the lines of</p>
  
  <pre><code>ALTER TABLE testTable ALTER COLUMN colA DROP NOT NULL;
  </code></pre>
  
  <p>which is what it would look like if I used PostgreSQL. To my amazement, as far as I've been able to find, the MySQL docs, Google and yes, even Stackoverflow (in spite of dozens or hundreds of NULL-related questions) don't seem to lead towards a single simple SQL statement which will do the job.</p>