title: Sqlite verify if value of column exists
body: <p>i'm wondering if this method is right to verify if the value of _username already exists in the column "username"</p>
  
  <pre><code>public boolean verification(String _username) throws SQLException{
      Cursor c = dataBase.rawQuery("SELECT * FROM "+TABLE_NAME+" WHERE "+KEY_USERNAME+"="+_username, null);
      if (c!=null)
          return true; // return true if the value of _username already exists
      return false; // Return false if _username doesn't match with any value of the columns "Username"
  }
  </code></pre>
  
  <p>Is there a better way to do the same thing, i'm really not sure about this, it seemed right for me.
  Thanks.  </p>