title: Removing Duplicated Entries: Delete a entry that has 2 the same column
body: <p>i have this table called <strong>bag</strong>:</p>
  
  <pre><code>+--------+----------+---------+----------+
  | bag_id | chara_id | item_id | item_qty |
  +--------+----------+---------+----------+
  |      1 |        1 |       2 |       22 |
  |      2 |        1 |       1 |       55 |
  |      3 |        3 |       1 |        2 |
  |      6 |        3 |       4 |        2 |
  |      7 |        4 |       4 |        2 |
  |      8 |        5 |       4 |        2 |
  |      9 |        6 |       4 |        2 |
  |     10 |        1 |       5 |        1 |
  |     11 |        1 |       2 |        1 |
  |     12 |        1 |       2 |        1 |
  |     13 |        1 |       2 |        1 |
  |     14 |        1 |       8 |        1 |
  |     15 |        1 |       6 |        1 |
  |     16 |        1 |       8 |        1 |
  |     17 |        1 |       6 |        1 |
  +--------+----------+---------+----------+
  </code></pre>
  
  <p>the relationship goes as 1 chara = many item
  now i dont want 1 chara = many duplicated item.</p>
  
  <p>how can i make a query that delete's the duplicated values?
  like chara_id: 1 has 3 duplicated item_id: 2 
  i want to delete the other 2.</p>