Getting Number of Rows using Left Join - php

Question

I have two tables, one is comments, and another is likesordislikes
comments
+----+--------+---------------+---------+
| id | userid | usercom | comname |
+----+--------+---------------+---------+
| 35 | 5 | check comment | 12 |
| 36 | 6 | comment test | 12 |
| 37 | 6 | third comment | 12 |
| 38 | 5 | number four | 12 |
| 39 | 7 | fifth | 13 |
| 40 | 4 | 6th | 13 |
| 41 | 18 | seven | 13 |
+----+--------+---------------+---------+
likesordislikes
+----+-------+------+-------+
| id | vtype | uid | comid |
+----+-------+------+-------+
| 1 | 0 | 5 | 35 |
| 2 | 1 | 6 | 35 |
| 3 | 1 | 7 | 35 |
| 4 | 0 | 8 | 36 |
| 5 | 1 | 5 | 36 |
| 6 | 1 | 9 | 35 |
| 7 | 1 | 10 | 36 |
| 8 | 1 | 11 | 36 |
| 9 | 1 | 20 | 35 |
| 10 | 0 | 9 | 35 |
| 11 | 1 | 21 | 37 |
+----+-------+------+-------+
In comments table userid is session id (logged in user) and comname is the post unique id on which comments are made by logged in users.
In likesordislikes table vtype is vote type where (0 = dislike , 1 = like), uid is logged in user id who likes or dislikes a comment and comid is from comments table (id) column
Now, i want to show total number of likes or dislikes under each comment for this specific comment.
the PHP code i am trying is here
$query1 = "SELECT
comments.id,
comments.usercom,
COUNT(likesordislikes.id) AS count
FROM
comments
LEFT JOIN likesordislikes ON
comments.id=likesordislikes.comid
WHERE likesordislikes.vtype='1'
GROUP BY
comments.id";
$query2 = "SELECT
comments.id,
comments.usercom,
COUNT(likesordislikes.id) AS count
FROM
comments
LEFT JOIN likesordislikes ON
comments.id=likesordislikes.comid
WHERE likesordislikes.vtype='0'
GROUP BY
comments.id";
$stmt = $DB->prepare($query1);
$stmt->execute();
$likes = $stmt->fetchAll();
$tlikes = count($likes);
$stmt = $DB->prepare($query2);
$stmt->execute();
$dislikes = $stmt->fetchAll();
$tdislikes = count($dislikes);
$slt = "SELECT * FROM `comments` where `comname` = '$c_name' and `post` = '$type'";
$res = mysqli_query($con, $slt);
while($fetch = mysqli_fetch_array($res)) {
echo $fetch['usercom']."<br />";
echo "Likes ".$tlikes."<br />";
echo "Dislikes ".$tdislikes;
}
that way, its not showing each comments likes/dislikes under that comment
in more clearer way, I want this result
Comments:
check comment
Likes 4 - Dislikes 2
comment test
Likes 3 - Dislikes 1
third comment
Likes 1 - Dislikes 0
number four
Likes - Dislikes
fifth
Likes - Dislikes
6th
Likes - Dislikes
seven
Likes - Dislikes
But its showing Likes 4 - Dislikes 2 on each comment on the article 12
Can anyone please check whats wrong in it?

Answer 1

You're basically getting all the likes and dislikes, for all the comments:
$query1 = "...";
$query2 = "...";
// ...
$tlikes = count($likes);
// ...
$tdislikes = count($dislikes);
And printing them for all the comments:
echo $fetch['usercom']."<br />";
echo "Likes ".$tlikes."<br />";
echo "Dislikes ".$tdislikes;
Which is why you're getting the same values for every comment. In order to fix your current code, you could create a map for $likes and $dislikes, like this:
$stmt = $DB->prepare($query1);
$stmt->execute();
$likes = array();
while($like = $stmt->fetch(PDO::FETCH_ASSOC){
$likes[$like['id']] = $like['count'];
}
And then, change your printing to something like:
while($fetch = mysqli_fetch_array($res)) {
echo $fetch['usercom']."<br />";
echo "Likes ".(empty($likes[$fetch['id']])?0:$likes[$fetch['id']])."<br />";
// ...
}
Note: You probably should filter the likes and dislikes queries the same way you filter the comments query (so you don't ask for things you won't use)
An alternative way is changing your three queries for a single one, which would change your code to something like this:
$slt =
"SELECT" .
" c.usercom," .
" SUM(CASE WHEN lod.vtype=1 THEN 1 ELSE 0 END) likes," .
" SUM(CASE WHEN lod.vtype=0 THEN 1 ELSE 0 END) dislikes" .
" FROM" .
" comments c LEFT JOIN likesordislikes lod ON lod.comid=c.id" .
" WHERE" .
" c.comname = '$c_name' AND c.post = '$type'" .
" GROUP BY" .
" c.id"
;
$res = mysqli_query($con, $slt);
while($fetch = mysqli_fetch_array($res)) {
echo $fetch['usercom']."<br />";
echo "Likes ".$fetch['likes']."<br />";
echo "Dislikes ".$fetch['dislikes'];
}
Here you have the query in case you want to see it working
Update
If you don't want to show two zeros, you could change your while to something like:
while($fetch = mysqli_fetch_array($res)) {
echo $fetch['usercom']."<br />";
if($fetch['likes']==='0' && $fetch['dislikes']==='0'){
$fetch['likes'] = '';
$fetch['dislikes'] = '';
}
echo "Likes ".$fetch['likes']."<br />";
echo "Dislikes ".$fetch['dislikes'];
}

Answer 2

Your query looks at the comname columns meaning it would give you everything for article 12 as you call it summed up and not separate for each of them.
You should be looking at the ids - something like
$slt = "SELECT * FROM `comments` where `id` = '$id' and `post` = '$type'";
where $id is the id in your comments table.
I am not sure how you can get this given the code you have shown but give it a try.