title: alter table script in sql
body: <p>If i have a table_abc. Now i alter and add few columns in this like </p>
  
  <pre><code>alter table_Abc add ( congif_id number, sso number);
  </code></pre>
  
  <p>Now second time i add few columns along with congif_id and sso like :</p>
  
  <pre><code>alter table_Abc add ( congif_id number, sso number,name varchar2(100));
  </code></pre>
  
  <p>but this is throwing error <code>column already exists.</code></p>
  
  <p>Shouldnt the alter script still run even if the names are same and add the new ones ?</p>