SQL Query is grabbing double the results - mysql

Question

I have an SQL Query that is grabbing the db for movies. This SQL query is only for showing the users history:
$movie = $db2->query("SELECT m.id AS mid,m.photo AS pho,
m.destination AS des,m.length AS len,
m.length_content AS lenc,m.description AS desa,m.rating AS rat,
m.files AS fil
FROM movies m
INNER JOIN history h ON h.movie_id = m.id
WHERE h.user_id = $id3
ORDER BY h.id
LIMIT $start, $per_page
");
while($movie3 = mysqli_fetch_array($movie)) {
$number++;
$id2 = $movie3["mid"];
$photo = $movie3["pho"];
$destination = $movie3["des"];
$length = $movie3["len"];
$length_content = $movie3["lenc"];
$description = $movie3["desa"];
$rating = $movie3["rat"];
$files = $movie3["fil"];
$friends_one = $db2->query("SELECT * FROM likes WHERE number_likes='$id2' LIMIT 2");
while($movie4 = mysqli_fetch_array($friends_one)) {
...
}
}
I have results that are doubling, it is not a problem with the server or db information. This is a photo of the problem:
This next image is going to show what the results are suppose to look like. This SQL Query follows the same db outline and while loops as history but uses a slightly different SQL query due to the structure of the db.
Code Associated with second image:
$movie = $db2->query("SELECT *
FROM movies m
INNER JOIN likes h ON h.number_likes = m.id
WHERE h.user = $id3
ORDER BY h.id
LIMIT $start, $per_page");
while($movie3 = mysqli_fetch_array($movie)) {
$number++;
$id2 = $movie3["id"];
$photo = $movie3["photo"];
$rating = $movie3["rating"];
$destination = $movie3["destination"];
$length = $movie3["length"];
$length_content = $movie3["length_content"];
$files = $movie3["files"];
$description = $movie3["description"];
$friends_one = $db2->query("SELECT * FROM likes WHERE number_likes='$id2' LIMIT 2");
while($movie4 = mysqli_fetch_array($friends_one)) {
...
}
}
I realize this is difficult to figure out. I'm new at programming and appreciate any help given...
EDIT: DDL For PhpmyAdmin
I'm not not quite sure if I did this right. Here are my results:
-- phpMyAdmin SQL Dump
-- version 4.4.14
-- http://www.phpmyadmin.net
--
-- Host: 127.0.0.1
-- Generation Time: Mar 15, 2016 at 12:30 PM
-- Server version: 5.6.26
-- PHP Version: 5.6.12
SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";
SET time_zone = "+00:00";
/*!40101 SET #OLD_CHARACTER_SET_CLIENT=##CHARACTER_SET_CLIENT */;
/*!40101 SET #OLD_CHARACTER_SET_RESULTS=##CHARACTER_SET_RESULTS */;
/*!40101 SET #OLD_COLLATION_CONNECTION=##COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8mb4 */;
--
-- Database: `crave crap`
--
-- --------------------------------------------------------
--
-- Table structure for table `episodes`
--
CREATE TABLE IF NOT EXISTS `episodes` (
`id` int(11) NOT NULL,
`show_id` int(11) NOT NULL,
`title` text NOT NULL,
`destination` text NOT NULL,
`description` text NOT NULL,
`length` text NOT NULL,
`likes` int(11) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
-- --------------------------------------------------------
--
-- Table structure for table `friends`
--
CREATE TABLE IF NOT EXISTS `friends` (
`id` int(11) NOT NULL,
`user` int(11) NOT NULL,
`grab` int(11) NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=17 DEFAULT CHARSET=latin1;
--
-- Dumping data for table `friends`
--
INSERT INTO `friends` (`id`, `user`, `grab`) VALUES
(13, 52, 51),
(14, 53, 51),
(15, 54, 51),
(16, 55, 51);
-- --------------------------------------------------------
--
-- Table structure for table `history`
--
CREATE TABLE IF NOT EXISTS `history` (
`id` int(11) NOT NULL,
`user_id` int(11) NOT NULL,
`movie_id` int(11) NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=90 DEFAULT CHARSET=latin1;
--
-- Dumping data for table `history`
--
INSERT INTO `history` (`id`, `user_id`, `movie_id`) VALUES
(80, 51, 7),
(81, 51, 8),
(82, 51, 9),
(83, 51, 11),
(84, 51, 11),
(85, 51, 11),
(86, 51, 11),
(87, 51, 11),
(88, 51, 11),
(89, 51, 11);
-- --------------------------------------------------------
--
-- Table structure for table `likes`
--
CREATE TABLE IF NOT EXISTS `likes` (
`id` int(11) NOT NULL,
`user` int(11) NOT NULL,
`number_likes` int(11) NOT NULL,
`review` text NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=150 DEFAULT CHARSET=latin1;
--
-- Dumping data for table `likes`
--
INSERT INTO `likes` (`id`, `user`, `number_likes`, `review`) VALUES
(130, 51, 9, 'gtgtgt'),
(131, 51, 8, 'gbgtrgrt'),
(132, 52, 8, 'tgrrgrgt'),
(135, 53, 8, 'tgrgtrgtr'),
(136, 53, 9, 'gtbrgtrgtrgtr'),
(137, 52, 11, 'tgrgtrgtr'),
(138, 53, 11, 'tgrgtrgtr'),
(139, 54, 11, 'tgrtgrbgtr'),
(140, 52, 12, 'tgrtgrgtr'),
(141, 53, 12, 'gtrgtrgtr'),
(143, 52, 9, 'ttrgth'),
(146, 51, 7, 'gtgtrtg'),
(147, 52, 7, 'tgtrgtrtr'),
(149, 51, 11, 'No Review Found');
-- --------------------------------------------------------
--
-- Table structure for table `movies`
--
CREATE TABLE IF NOT EXISTS `movies` (
`id` int(11) NOT NULL,
`title` text NOT NULL,
`photo` text NOT NULL,
`destination` text NOT NULL,
`description` text NOT NULL,
`rating` text NOT NULL,
`length` text NOT NULL,
`length_content` text NOT NULL,
`likes` int(11) NOT NULL,
`files` int(11) NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=19 DEFAULT CHARSET=latin1;
--
-- Dumping data for table `movies`
--
INSERT INTO `movies` (`id`, `title`, `photo`, `destination`, `description`, `rating`, `length`, `length_content`, `likes`, `files`) VALUES
(7, 'Star Inside Out', 'covers/pirate.jpg', 'movies/56c7ede7d3ed3658.44679765.mp4', 'Professional, Clean, Ready to Go', 'G', '1h 20m', '1', 6, 3),
(8, 'Star Wars', 'covers/star wars.jpg', 'movies/56c7ede7d3ed3108.44679765.mp4', 'Thirty years after the defeat of the Galactic Empire, the galaxy faces a new threat from the evil Kylo Ren (Adam Driver) and the First Order. When a defector named Finn crash-lands on a desert planet, he meets Rey (Daisy Ridley), a tough scavenger whose droid contains a top-secret map. Together, the young duo joins forces with Han Solo (Harrison Ford) to make sure the Resistance receives the intelligence concerning the whereabouts of Luke Skywalker (Mark Hamill), the last of the Jedi Knights.', 'PG', '2h 16m', '1', 100, 100),
(9, 'Hello', 'covers/56e068530dc9f9.52895782.jpg', 'movies/56e06853166618.33290858.mp4', 'Hello', 'PG-13', '58m', '0', 27, 12),
(11, 'The lost boy', 'covers/56e4341b6bb3f5.36887672.jpg', 'movies/56e4341b6bd319.33767547.mp4', 'A boy gets lost in the forest, separating him from his family, he must learn how to survive long enough to get out alive.', 'PG-13', '1h 47m', '1', 29, 58),
(12, 'The lost boy', 'covers/56e4341b6bb3f5.36887672.jpg', 'movies/56e4341b6bd319.33767547.mp4', 'A boy gets lost in the forest, separating him from his family, he must learn how to survive long enough to get out alive.', 'PG-13', '1h 47m', '1', 30, 60),
(14, 'The lost boy', 'covers/56e4341b6bb3f5.36887672.jpg', 'movies/56e4341b6bd319.33767547.mp4', 'A boy gets lost in the forest, separating him from his family, he must learn how to survive long enough to get out alive.', 'PG-13', '1h 47m', '1', 33, 60),
(15, 'The lost boy', 'covers/56e4341b6bb3f5.36887672.jpg', 'movies/56e4341b6bd319.33767547.mp4', 'A boy gets lost in the forest, separating him from his family, he must learn how to survive long enough to get out alive.', 'PG-13', '1h 47m', '1', 30, 60),
(16, 'The lost boy', 'covers/56e4341b6bb3f5.36887672.jpg', 'movies/56e4341b6bd319.33767547.mp4', 'A boy gets lost in the forest, separating him from his family, he must learn how to survive long enough to get out alive.', 'PG-13', '1h 47m', '1', 34, 60),
(17, 'The lost boy', 'covers/56e4341b6bb3f5.36887672.jpg', 'movies/56e4341b6bd319.33767547.mp4', 'A boy gets lost in the forest, separating him from his family, he must learn how to survive long enough to get out alive.', 'PG-13', '1h 47m', '1', 32, 60),
(18, 'The lost boy', 'covers/56e4341b6bb3f5.36887672.jpg', 'movies/56e4341b6bd319.33767547.mp4', 'A boy gets lost in the forest, separating him from his family, he must learn how to survive long enough to get out alive.', 'PG-13', '1h 47m', '1', 32, 60);
-- --------------------------------------------------------
--
-- Table structure for table `shows`
--
CREATE TABLE IF NOT EXISTS `shows` (
`id` int(11) NOT NULL,
`title` text NOT NULL,
`photo` text NOT NULL,
`description` text NOT NULL,
`likes` int(11) NOT NULL,
`seasons` int(11) NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=latin1;
--
-- Dumping data for table `shows`
--
INSERT INTO `shows` (`id`, `title`, `photo`, `description`, `likes`, `seasons`) VALUES
(1, 'Age of Ultron', 'covers/56c6961452b097.49801377.jpg', 'Hello', 5, 2);
-- --------------------------------------------------------
--
-- Table structure for table `show_likes`
--
CREATE TABLE IF NOT EXISTS `show_likes` (
`id` int(11) NOT NULL,
`user` int(11) NOT NULL,
`number_likes` int(11) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
-- --------------------------------------------------------
--
-- Table structure for table `users`
--
CREATE TABLE IF NOT EXISTS `users` (
`id` int(11) NOT NULL,
`username` text NOT NULL,
`password` text NOT NULL,
`dropbox_token` text NOT NULL,
`active` int(11) NOT NULL,
`premium` int(11) NOT NULL,
`avatar` text NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=63 DEFAULT CHARSET=latin1;
--
-- Dumping data for table `users`
--
INSERT INTO `users` (`id`, `username`, `password`, `dropbox_token`, `active`, `premium`, `avatar`) VALUES
(51, 'MatthewMalan', '76a7289eb67f6468356cba907809f2fd', 'kLQQAh1zJSAAAAAAAAABjaQvSFyq0RxKylBPtSL3-PM7uKRDaATZunClQ1Zsv24F', 0, 1, 'avatars/matthew.jpg'),
(52, 'Sam Coles', '91d9dfc1fef07bbcf46fe06f659e8cb3', 'kLQQAh1zJSAAAAAAAAAB48QKdqo-X0nN99I_3bxbFMKRtSdwbsrBz00yO_0P0XAB', 0, 1, 'avatars/sam.jpg'),
(53, 'Traek Malan', '91d9dfc1fef07bbcf46fe06f659e8cb3', 'kLQQAh1zJSAAAAAAAAAB48QKdqo-X0nN99I_3bxbFMKRtSdwbsrBz00yO_0P0XAB', 0, 1, 'avatars/traek.jpg'),
(54, 'Jesse Gaines', '91d9dfc1fef07bbcf46fe06f659e8cb3', 'kLQQAh1zJSAAAAAAAAAB48QKdqo-X0nN99I_3bxbFMKRtSdwbsrBz00yO_0P0XAB', 0, 1, 'avatars/jessie.jpg'),
(55, 'Rich Radford', '91d9dfc1fef07bbcf46fe06f659e8cb3', 'kLQQAh1zJSAAAAAAAAAB48QKdqo-X0nN99I_3bxbFMKRtSdwbsrBz00yO_0P0XAB', 0, 1, 'avatars/rich.jpg'),
(58, 'Donald Trump', '91d9dfc1fef07bbcf46fe06f659e8cb3', 'kLQQAh1zJSAAAAAAAAAB48QKdqo-X0nN99I_3bxbFMKRtSdwbsrBz00yO_0P0XAB', 0, 1, 'avatars/donald.jpg'),
(59, 'Marco Rubio', '91d9dfc1fef07bbcf46fe06f659e8cb3', 'kLQQAh1zJSAAAAAAAAAB48QKdqo-X0nN99I_3bxbFMKRtSdwbsrBz00yO_0P0XAB', 0, 1, 'avatars/marco.jpg'),
(62, 'Joseph Malan', '91d9dfc1fef07bbcf46fe06f659e8cb3', 'kLQQAh1zJSAAAAAAAAAB5mCiOhnPi2nNKr7bhFLnOC8LVRMiLvdI30CNgSJNOygm', 0, 1, 'default');
--
-- Indexes for dumped tables
--
--
-- Indexes for table `episodes`
--
ALTER TABLE `episodes`
ADD PRIMARY KEY (`id`);
--
-- Indexes for table `friends`
--
ALTER TABLE `friends`
ADD PRIMARY KEY (`id`);
--
-- Indexes for table `history`
--
ALTER TABLE `history`
ADD PRIMARY KEY (`id`);
--
-- Indexes for table `likes`
--
ALTER TABLE `likes`
ADD PRIMARY KEY (`id`);
--
-- Indexes for table `movies`
--
ALTER TABLE `movies`
ADD PRIMARY KEY (`id`);
--
-- Indexes for table `shows`
--
ALTER TABLE `shows`
ADD PRIMARY KEY (`id`);
--
-- Indexes for table `show_likes`
--
ALTER TABLE `show_likes`
ADD PRIMARY KEY (`id`);
--
-- Indexes for table `users`
--
ALTER TABLE `users`
ADD PRIMARY KEY (`id`);
--
-- AUTO_INCREMENT for dumped tables
--
--
-- AUTO_INCREMENT for table `episodes`
--
ALTER TABLE `episodes`
MODIFY `id` int(11) NOT NULL AUTO_INCREMENT;
--
-- AUTO_INCREMENT for table `friends`
--
ALTER TABLE `friends`
MODIFY `id` int(11) NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=17;
--
-- AUTO_INCREMENT for table `history`
--
ALTER TABLE `history`
MODIFY `id` int(11) NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=90;
--
-- AUTO_INCREMENT for table `likes`
--
ALTER TABLE `likes`
MODIFY `id` int(11) NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=150;
--
-- AUTO_INCREMENT for table `movies`
--
ALTER TABLE `movies`
MODIFY `id` int(11) NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=19;
--
-- AUTO_INCREMENT for table `shows`
--
ALTER TABLE `shows`
MODIFY `id` int(11) NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=2;
--
-- AUTO_INCREMENT for table `show_likes`
--
ALTER TABLE `show_likes`
MODIFY `id` int(11) NOT NULL AUTO_INCREMENT;
--
-- AUTO_INCREMENT for table `users`
--
ALTER TABLE `users`
MODIFY `id` int(11) NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=63;
/*!40101 SET CHARACTER_SET_CLIENT=#OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=#OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=#OLD_COLLATION_CONNECTION */;
EDIT #trincot
This is the code I used:
$movie = $db2->query("SELECT m.id AS mid, m.photo AS pho,
m.destination AS des, m.length AS len,
m.length_content AS lenc, m.description AS desa, m.rating AS rat,
m.files AS fil
FROM movies m
INNER JOIN
( SELECT movie_id, MAX(id) AS id,
FROM history
WHERE h.user_id = $id3
GROUP BY movie_id
) h ON h.movie_id = m.id
ORDER BY h.id
LIMIT $start, $per_page");
$movie connects to a while loop. $id3 is the users id, which is found by a session. $start and $per_page are used for pagination purposes.

Answer 1

The duplicates
The DDL section shows you have duplicates in the history table, which in itself is not a problem, but it does explain the duplicate results you get in your query.
The solution is to filter away the duplicate history records, and keep only the most recent from them for the rest of the query. This filtering you can do in a sub query, like this:
SELECT m.id AS mid,
m.photo AS pho,
m.destination AS des,
m.length AS len,
m.length_content AS lenc,
m.description AS desa,
m.rating AS rat,
m.files AS fil
FROM movies m
INNER JOIN (
SELECT movie_id,
MAX(id) AS id
FROM history
WHERE user_id = ?
GROUP BY movie_id
) h ON h.movie_id = m.id
ORDER BY h.id
LIMIT ?, ?
(If SQL fiddle is willing to work, here is a fiddle).
The essence is in the GROUP BY movie_id which ensures you will not get duplicate movies. At the same time you take the greatest id from that group, which corresponds to the most recent one of that group, and this is important for the outer ORDER BY.
The question marks are place holders to be replaced when you prepare the statement (see below).
In the second version of the query, you don't select from history, but from likes. I assume you really want to select from history. If however, you want to only show movies that appear for this user in the likes table, you must either make sure the combination of movie and user is unique in that table, or apply the same principle as above, i.e. perform a sub query.
Prepared statements
You should use prepared statements to avoid SQL injection. Here is how you would do it:
$sql = ' ... '; // insert above query here
$stmt_movies = $db2->prepare($sql);
$stmt_movies->bind_param("iii", $user_id, $start, $per_page);
$stmt_movies->execute() or die($stmt_movies->error);
$stmt_movies->store_result();
$stmt_movies->bind_result($movie_id, $photo, $destination, $length,
$length_content, $description; $rating, $files);
while ($stmt_movies->fetch()) {
//...
}
$stmt_movies->free_result();
The second query
It is really confusing to use the name number_likes for a column that apparently holds a movie id. I would recommend to change that name to movie_id. The fact that it concerns a like is already apparent from the table name.
Secondly, it is just as confusing to select from the table likes and then call the result $friends_one. As far as I can tell a record in the table likes indicates that a user likes a certain movie, and potentially records a review written by that user. It does not have any information about friends... A better name would be $movie_likers.
You limit the number of records to two, but have no control over which two will be taken. It would be better if you would add an ORDER BY clause.
Finally, you should either combine this query with the main query, or at least prepare it, so it is compiled once, and not in every iteration. Here is how that would look (with some change to variable names, see below):
$sql = "SELECT review FROM likes WHERE number_likes = ? ORDER BY id DESC LIMIT 2";
$stmt_likes = $db2->prepare($sql);
$stmt_likes->bind_param("i", $move_id);
Then combined with the other code, you get this code:
$sql = ' ... '; // insert above query here
$stmt_movies = $db2->prepare($sql);
$stmt_movies->bind_param("iii", $movie_id, $start, $per_page);
$stmt_movies->execute() or die($stmt_movies->error);
$stmt_movies->store_result();
$stmt_movies->bind_result($movie_id, $photo, $destination, $length,
$length_content, $description; $rating, $files);
$sql = "SELECT review FROM likes WHERE number_likes = ? ORDER BY id DESC LIMIT 2";
$stmt_likes = $db2->prepare($sql);
while ($stmt_movies->fetch()) {
$stmt_likes->bind_param("i", $movie_id);
$stmt_likes->execute() or die($stmt_likes->error);
$stmt_likes->store_result();
$stmt_likes->bind_result($review);
while ($stmt_likes->fetch()) {
//...
}
$stmt_likes->free_result();
//...
}
$stmt_movies->free_result();
Choose telling variable names
As already hinted above, the names of the variables should better not be $id3, $id2, $movie4, ... etc. Try to use more telling names, like user_id, movie_id, etc. It helps to understand the code -- especially when you come back to it after a few months.

Answer 2

The first query joins the history table, but does not select from it. So you receive as many records per movie as there are history entries for the movie.