PHP MysqlI - How to Select 1 Row? (from select) - php

Question

I am a bit stumped on how i should be able to Define 1 post ID, and only select from that row
my query:
SELECT
posts.post_id,
posts.title,
COUNT(post_likes.id) AS likes,
GROUP_CONCAT(user.name SEPARATOR '|') AS liked
FROM
posts
LEFT JOIN post_likes ON post_likes.post_id = posts.post_id
LEFT JOIN user ON post_likes.user = user.id
GROUP BY
posts.post_id
my end goal is to get all from row 3 (only row 3), not get all rows. when i run the query above, i get every row from mysql.
example:
$query = "
SELECT
posts.post_id,
posts.title,
COUNT(post_likes.id) AS likes,
GROUP_CONCAT(user.name SEPARATOR '|') AS liked
FROM
posts
LEFT JOIN post_likes ON post_likes.post_id = posts.post_id
LEFT JOIN user ON post_likes.user = user.id
GROUP BY
posts.post_id
";
$result = mysqli_query($connect, $query);
while($row = mysqli_fetch_array($result))
{
echo '<h3>'.$row["title"].'</h3>';
echo 'Like';
echo '<p>'.$row["likes"].' People like this</p>';
if(count($row["liked"]))
{
$liked = explode("|", $row["liked"]);
echo '<ul>';
foreach($liked as $like)
{
echo '<li>'.$like.'</li>';
}
echo '</ul>';
}
}
returns with all rows,
what i need to do is just return the 3rd row (from the post_id, and only that row)
CREATE TABLE IF NOT EXISTS `posts` (
`post_id` int(11) NOT NULL AUTO_INCREMENT,
`title` text,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=5 ;
-- posts
INSERT INTO `posts` (`id`, `title`) VALUES
(1, 'Ajax Jquery Drag and Drop Shopping Cart using PHP Mysql'),
(2, 'Make PHP Hashtag system by using Regular Expression'),
(3, 'Ajax Jquery Column Sort with PHP & MySql'),
(4, 'Drag and drop Upload multiples File By Ajax JQuery PHP');
--
CREATE TABLE IF NOT EXISTS `post_likes` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`user` int(11) NOT NULL,
`post` int(11) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=46 ;
--table
CREATE TABLE IF NOT EXISTS `user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` text NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ;
--
INSERT INTO `user` (`id`, `name`) VALUES
(1, 'john'),
(2, 'jack');
CREATE TABLE `post_likes` (
`id` int NOT NULL,
`user` int NOT NULL,
`post_id` int NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
--
-- Dumping data for table `post_likes`
--
INSERT INTO `post_likes` (`id`, `user`, `post_id`) VALUES
(11111, 3, 3),
(91, 2, 3);
final edit, i kinda just said screw it and just did this:
$query1 = 'SELECT * FROM posts WHERE post_id = "$page_id"';
$result1 = mysqli_query($connect, $query1);
$query2 = 'SELECT * FROM post_likes WHERE post_id = "$page_id"';
$result2 = mysqli_query($connect, $query2);
if ($result3 = $connect->query('SELECT * FROM post_likes WHERE post_id = "'.$page_id.'"')) {
$row_cnt = $result3->num_rows;
printf("Result set has %d rows.\n", $row_cnt);
}
thanks to all who helped though, i really appreciate it.

Answer 1

You can use the function ROW_NUMBER() (MySQL 8 MariaDB 10.4)
The principal thing is, that MySQL needs an order to determine which row number is what
I selected
OVER(ORDER BY COUNT(post_likes.id))
But it can be every column from the from clause
CREATE TABLE IF NOT EXISTS `posts` (
`post_id` int(11) NOT NULL AUTO_INCREMENT,
`title` text,
PRIMARY KEY (`post_id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=5 ;
-- posts
INSERT INTO `posts` (`post_id`, `title`) VALUES
(1, 'Ajax Jquery Drag and Drop Shopping Cart using PHP Mysql'),
(2, 'Make PHP Hashtag system by using Regular Expression'),
(3, 'Ajax Jquery Column Sort with PHP & MySql'),
(4, 'Drag and drop Upload multiples File By Ajax JQuery PHP');
--
CREATE TABLE IF NOT EXISTS `post_likes` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`user` int(11) NOT NULL,
`post` int(11) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=46 ;
--table
CREATE TABLE IF NOT EXISTS `user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` text NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ;
--
INSERT INTO `user` (`id`, `name`) VALUES
(1, 'john'),
(2, 'jack');
WITH CTE AS (SELECT
posts.post_id,
posts.title,
COUNT(post_likes.id) AS likes,
GROUP_CONCAT(user.name SEPARATOR '|') AS liked
,ROW_NUMBER() OVER(ORDER BY COUNT(post_likes.id)) rn
FROM
posts
LEFT JOIN post_likes ON post_likes.post = posts.post_id
LEFT JOIN user ON post_likes.user = user.id
GROUP BY
posts.post_id)
SELECT post_id,title, likes,liked FROM CTE WHERE rn = 3
post_id | title | likes | liked
------: | :--------------------------------------- | ----: | :----
3 | Ajax Jquery Column Sort with PHP & MySql | 0 |
SELECT post_id,title, likes,liked FROM
(SELECT
posts.post_id,
posts.title,
COUNT(post_likes.id) AS likes,
GROUP_CONCAT(user.name SEPARATOR '|') AS liked
,ROW_NUMBER() OVER(ORDER BY COUNT(post_likes.id)) rn
FROM
posts
LEFT JOIN post_likes ON post_likes.post = posts.post_id
LEFT JOIN user ON post_likes.user = user.id
GROUP BY
posts.post_id) t1
WHERE rn = 3
post_id | title | likes | liked
------: | :--------------------------------------- | ----: | :----
3 | Ajax Jquery Column Sort with PHP & MySql | 0 |
db<>fiddle here