title: using sqlite create virtual table using fts3 with unique column dosnot stay unique
body: <p>im creating (in Qt ) </p>
  
  <pre><code>QString q = "CREATE VIRTUAL TABLE playlist USING fts3 ("
                          "from_user , " 
                          "from_id , "
                          "created_time , "
                          "created_time_formated , "
                          "user_id unique )";
  </code></pre>
  
  <p>then execute </p>
  
  <pre><code>"INSERT OR IGNORE INTO  play_list (from_user,from_id,created_time,created_time_formated,user_id) SELECT '....','....','.....','....','123'"  
  </code></pre>
  
  <p>im using full Full-Text Search so this is way im using VIRTUAL TABLE  </p>
  
  <p>if i have another row with user_id == 123 it will still insert the row , why ?  </p>