How to query unique data and count?

How to query unique data and count?

CREATE TABLE IF NOT EXISTS `tab1` (
  `id` int(6) unsigned NOT NULL,
  `rev` int(3) unsigned NOT NULL,
  `content` varchar(200) NOT NULL,
  PRIMARY KEY (`id`,`rev`)
) DEFAULT CHARSET=utf8;
INSERT INTO `tab1` (`id`, `rev`, `content`) VALUES
  ('1', '1', 'The earth is flat'),
  ('2', '1', 'One hundred angels can dance on the head of a pin'),
  ('1', '2', 'The earth is flat and rests on a bull\'s horn'),
  ('1', '3', 'The earth is like a ball.');
CREATE TABLE IF NOT EXISTS `tab2` (
  `id` int(6) unsigned NOT NULL,
  `rev` int(3) unsigned NOT NULL,
  `content` varchar(200) NOT NULL,
  PRIMARY KEY (`id`,`rev`)
) DEFAULT CHARSET=utf8;
INSERT INTO `tab2` (`id`, `rev`, `content`) VALUES
  ('1', '1', 'The earth is flat'),
  ('2', '1', 'One hundred angels can dance on the head of a pin'),
  ('1', '2', 'The earth is flat and rests on a bull\'s horn'),
  ('1', '3', 'The earth is like a ball.');

SELECT tab1.id as tab1_id, tab2.id as tab2_id, 
COUNT(*) as qtde
FROM `tab1` tab1
INNER JOIN (SELECT id FROM `tab2`) tab2 
ON tab1.id = tab2.id
GROUP BY tab1.id, tab2.id
order by qtde;

SELECT *
FROM `tab1` tab1
INNER JOIN (SELECT id FROM `tab2`) tab2 
ON tab1.id = tab2.id;