title: how to remove default constraint from column in Db2
body: <p>I had a table STUDENT_TB, which had column STUDENT_ID, NAME, AGE. I added a column with a following command :- </p>
  
  <pre><code>alter table STUDENT_TB add DOB TIMESTAMP NOT NULL DEFAULT CURRENT TIMESTAMP
  </code></pre>
  
  <p>as for the DOB column i didn't wanted it to be null. Now i need to remove that default constraint.</p>
  
  <p>I tried searching but not got any success.</p>
  
  <p>Regards.</p>