code: public function toSQLString() {
      if ($this->operator=='IN') {
      	$sql = '(';
  	    $komma = '';
  	    for ($i=0;$i<count($this->operation);$i++)
  	    {
  	      $sql.= $komma.'?';
  	      $komma = ',';
  	    }
  	    $sql.= ')';
  	    return $sql;
      } elseif ($this->operator=='BETWEEN') {
      	return '? AND ?';
      }
    }
docs: This method is called by Web2All_Table_SaveObject when
  inserting or updating an object with a Web2All_Table_SQLOperation
  as value.
  
  @return string