Antal tomme (null) i databasen og andre regnestykker

CREATE TABLE `ordliste` (
  `id` int(11) NOT NULL,
  `ord_engelsk` varchar(255) COLLATE utf8_danish_ci NOT NULL,
  `ord_dansk` varchar(255) COLLATE utf8_danish_ci NOT NULL,
  `ord_svensk` varchar(255) COLLATE utf8_danish_ci NOT NULL,
  `ord_tysk` varchar(255) COLLATE utf8_danish_ci NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_danish_ci;

INSERT INTO `ordliste` (`id`, `ord_engelsk`, `ord_dansk`, `ord_svensk`, `ord_tysk`) VALUES
(1, 'cat', 'kat', '', ''),
(2, 'dog', 'hund', '', ''),
(3, 'horse', 'hest', '', ''),
(4, 'pig', 'gris', '', ''),
(5, 'goat', 'ged', '', ''),
(6, 'rabbit', 'kanin', '', '');

ALTER TABLE `ordliste`
  ADD PRIMARY KEY (`id`);

ALTER TABLE `ordliste`
  MODIFY `id` int(11) NOT NULL AUTO_INCREMENT, AUTO_INCREMENT=7;COMMIT;

SELECT COUNT(id) AS norows, COUNT(ord_dansk) AS nodk, COUNT(ord_svensk) AS nosv, COUNT(ord_engelsk) AS noen, COUNT(ord_tysk) AS noty FROM ordliste

SELECT COUNT(id) AS norows, COUNT(IF(ord_dansk !='',1 ,NULL)) AS nodk, COUNT(IF(ord_svensk !='',1 ,NULL)) AS nosv, COUNT(IF(ord_engelsk !='',1 ,NULL)) AS noen, COUNT(IF(ord_tysk !='',1 ,NULL)) AS noty FROM ordliste

SELECT COUNT(id) AS norows,
SUM(IF(ord_dansk !='',1 ,0)) AS nodk,
SUM(IF(ord_svensk !='',1 ,0)) AS nosv,
SUM(IF(ord_engelsk !='',1 ,0)) AS noen,
SUM(IF(ord_tysk !='',1 ,0)) AS noty
FROM ordliste

SELECT COUNT(id) AS norows,
SUM( CASE WHEN ord_dansk !='' THEN 1 ELSE 0 END ) AS nodk,
SUM( CASE WHEN ord_svensk !='' THEN 1 ELSE 0 END ) AS nosv,
SUM( CASE WHEN ord_engelsk !='' THEN 1 ELSE 0 END ) AS noen,
SUM( CASE WHEN ord_tysk !='' THEN 1 ELSE 0 END ) AS noty
FROM ordliste