title: SQLite: Delete duplicate entries
body: <p>I am new to SQLite and I would like to find a solution to deleting duplicate entries based on a certain condition.
  Suppose I have a table like this:</p>
  
  <pre><code>ID | Person1 | ID1 | Person2 | ID2 | Average
  -------------------------------------------
  1  | Name1   |   1  | Name4 |   4  | 47
  2  | Name1   |   1  | Name5 |   5  | 88
  3  | Name1   |   1  | Name6 |   6  | 15
  ----------------------------------------
  4  | Name2   |   2  | Name4 |   4  | 90
  5  | Name2   |   2  | Name5 |   5  | 80
  6  | Name2   |   2  | Name6 |   6  | 45
  ----------------------------------------
  7  | Name3   |   3  | Name4 |   4  | 30
  8  | Name3   |   3  | Name5 |   5  | 20
  9  | Name3   |   3  | Name6 |   6  | 79
  </code></pre>
  
  <p>and want a table like this:</p>
  
  <pre><code>ID | Person1 | ID1 | Person2 | ID2  | Average
  -------------------------------------------
  2  | Name1   |   1  | Name5 |   5   | 88
  5  | Name2   |   2  | Name4 |   4   | 90
  9  | Name3   |   3  | Name6 |   6   | 79
  </code></pre>
  
  <p>Is there anyway of doing this?
  Thanks in advance.</p>