title: How to insert null value when doing left join in SQL
body: <p>I have these 2 table (each element is in column):</p>
  
  <pre><code>TABLE A: 
  ID  1  2  3 4 5
  TD  20 10 0 1 7
  
  TABLE B:
  ID  2  3 
  TD  40 30 
  </code></pre>
  
  <p>I want to do a LEFT JOIN to obtain a FINAL_TABLE in which I have all the ID od TABLE A and the one of table B in common with A. I want also that in case there is ID in TABLE A and not in TABLE B (ex. ID 1,4,5), in the FINAL_TABLE I will show NULL at that ID.
  The FINAL_TABLE should be (see all in column):</p>
  
  <pre><code>ID  1    2  3  4    5
  TDA 20   10 0  1    7
  TDB NULL 40 30 NULL NULL
  </code></pre>
  
  <p>How can I achieve that?</p>