php duplicate item

          $sql = "SELECT md_day from ". tblMain ." where md_day BETWEEN ".$val." AND DATE_SUB( ".$val.", INTERVAL 1 MONTH ) ";
          $query = DBC::get()->prepare( $sql );
          $query->execute();
          $results = $query->fetchAll();
          $str_date = "";

          foreach( $results as $row )
          {
            $str_date = $str_date ." - ". $row['md_day'];
          }


  function validate_md_day($col,$val,$row,$instanceName)
  {
    if($row['id']) // check if edit or add.
    {
      $add = false; $edit = true;
       $this->Editor->addTooltipMsg('record is being EDITED ');

       $query = "SELECT * from ". tblMain ." where md_day = :md_day";
       $queryParams = array('md_day' => $val);
       $stmt = DBC::get()->prepare($query);
       $stmt->execute($queryParams);
        if($row = $stmt->fetch())
        {
          $this->Editor->showDefaultValidationMsg = false;
          $this->Editor->addTooltipMsg('There is already a row with id = ' . $row['id'] );
          return false;
        }
        else
        {
          $this->Editor->showDefaultValidationMsg = false;
          $this->Editor->addTooltipMsg('Entered date is available ' . $val );
          return false;
        }
    }
    else
    {
      // Record is being added.
      $query = "SELECT * from ". tblMain ." where md_day = :md_day";
      $queryParams = array('md_day' => $val);
      $stmt = DBC::get()->prepare($query);
      $stmt->execute($queryParams);

      if($row = $stmt->fetch())
      {
          $this->Editor->showDefaultValidationMsg = false;
          $this->Editor->addTooltipMsg('Following dates are already taken. = '  );
          return false;
        }
        else
        {
          $this->Editor->showDefaultValidationMsg = false;
          $this->Editor->addTooltipMsg('Entered date is available & ok ' . $val );
          return true;
        }
    }
  }


          $sql = "SELECT md_day from ". tblMain ." where md_day BETWEEN ".$val." AND DATE_SUB( ".$val.", INTERVAL 1 MONTH ) ";
          $query = DBC::get()->prepare( $sql );
          $query->execute();
          $results = $query->fetchAll();
          $str_date = "";

          foreach( $results as $row )
          {
            $str_date = $str_date ." - ". $row['md_day'];
          }