title: What is the "Null" Column in Describe statement?
body: <p>What does the "Null" column mean in the results of <code>DESCRIBE</code>?</p>
  
  <p>Ex:  </p>
  
  <pre><code>decribe table1;
  
  Name                 Null       Type
  ------------------  ----------  ---------------
  Number                          Number(5)
  Name                            Varchar2(25)
  DeptNo              NotNull     Number(5)
  </code></pre>