title: how do you JOIN two tables without using common column?
body: <pre><code>Table 1                               Table 2
  
  Column1    Column2    Column3         Column4    Column5    Column3
  -------    -------    -------         -------    -------    -------
  A          1          a               E          10         a
  B          2          b               F          11         b
  C          3          c               G          12         c
  D          4          d               H          13         d
  
  
  Table 3                               Table 4  
  
  Column6    Column7    Column4         Column8    Column9    Column6
  -------    -------    -------         -------    -------    -------
  I          20         E               M          30         I
  J          21         F               N          31         J
  K          22         G               O          32         K
  L          23         H               P          33         L
  </code></pre>
  
  <p>Expected Output</p>
  
  <pre><code>Column1    Column9
  -------    -------
  C          31
  C          32
  C          33
  </code></pre>
  
  <p>How do I get the output to look at the expected above?</p>
  
  <p>This is for my Oracle SQL course I am currently taking. Although the tables have common columns, the question ask <strong>NOT</strong> to use the common columns and instead use a different column to get the expected output while getting rid of duplicates.</p>