How to select comments with child comments from MySQL? - php

Question

I have two tables:
'comments'
| id | content | user_id | article_id | parent_id |
'users'
| id | name | photo |
And my queries are:
<?php
$query = mysql_query("SELECT comments.id, comments.content, users.name,
users.photo FROM comments, users WHERE comments.article_id = '".$get_id."'
AND comments.parent_id = 0 AND comments.user_id = users.id");
while($res = mysql_fetch_assoc($query))
{
$id = $res['id'];
$content = $res['content'];
$name = $res['name'];
$photo = $res['photo'];
echo $photo;
echo $name;
echo $content;
$query2 = mysql_query("SELECT comments.id, comments.content, users.name,
users.photo FROM comments, users WHERE comments.article_id = '".$get_id."'
AND comments.parent_id = '".$id."' AND comments.user_id = users.id");
while($res2 = mysql_fetch_assoc($query2))
{
$id2 = $res2['id'];
$content2 = $res2['content'];
$name2 = $res2['name'];
$photo2 = $res2['photo'];
echo $photo2;
echo $name2;
echo $content2;
}
}
?>
It doesn't work properly. It shows 1 parent and 1 child comment in each nest although there are several child comments.
How can I fix and minimize it? Can it be done by using only one query?
Thank you!

Answer 1

JOIN the table on itself.
Change your query to:
SELECT comments.id, comments.content, users.name,
users.photo FROM comments JOIN users ON comments.user_id = users.id JOIN
comments c ON comments.id =
c.parent_id WHERE
comments.article_id = '".$get_id."'
AND comments.parent_id = '".$id."'
You don't need the second query, here's the full code:
<?php
$query = mysql_query("SELECT comments.id, comments.content, users.name,
users.photo FROM comments JOIN users ON comments.user_id = users.id JOIN
comments c ON comments.id =
c.parent_id WHERE
comments.article_id = '".$get_id."'");
while($res = mysql_fetch_assoc($query))
{
$id = $res['id'];
$content = $res['content'];
$name = $res['name'];
$photo = $res['photo'];
echo $photo;
echo $name;
echo $content;
}
?>

Answer 2

Just use a JOIN to fetch the comments and with all the children.
SELECT users.id userID, users.name, users.photo , childrenComments.*,
parentComments.id cpId, parentComments.content cpContent,
parentComments.user_id cpUser_id,parentComments.article_id cpArticleId
FROM users JOIN (SELECT * FROM Comment WHERE id=0) parentComments
ON users.id=parentComments.user_id LEFT JOIN Comment childrenComments
ON parentComments.id=childrenComments.parent_id;
Then you can the loop through the result to print it appropriately. This would be better as you would have to run just a single query.