title: Disabling the Not-Nullable field in ORACLE to insert NULL data
body: <p>I have to add some NULL data into an otherwise not-nullable field. I checked :- </p>
  
  <p><code>ALTER TABLE &lt;table_name&gt; DROP &lt;default_constraint_name&gt; ;</code></p>
  
  <p><code>ALTER TABLE &lt;table_name&gt; ALTER COLUMN &lt;column_name&gt; &lt;data_type&gt; NULL;</code></p>
  
  <p><code>ALTER TABLE &lt;table_name&gt; DROP COLUMN &lt;column_name&gt;;</code></p>
  
  <p>but only the middle one seems fit for my usage because all I want o do is alter instead of . But it does not work. I am using Oracle 11g. Could you suggest anyother method or suggest what mistake I am doing in the 2nd ALTER TABLE SQL?</p>