title: import null value (date type) from txt file to oracle by Oracle SQL developer
body: <p>i have a table: </p>
  
  <pre><code>CREATE TABLE tmpTable 
  ( 
    firstDay date, 
    lastDay date, 
    description char(50) 
  ); 
  </code></pre>
  
  <p>i have a text file include these data:</p>
  
  <pre><code>-------------------------
  | 08/27/2017 null "khanh" | 
  | null 08/27/2017 "khanh" | 
  </code></pre>
  
  <p>i used Oracle SQL Developer to load data from .txt file to my table but it doesn't recognize the null field <br></p>
  
  <p><a href="https://i.stack.imgur.com/hoSnZ.png" rel="nofollow noreferrer">link</a></p>
  
  <p>How can i import data in .txt file with null value</p>