INSERT INTO with joins? - mysql

Question

I got trouble inserting data to a table that has joins to other tables, I've never done that before and the searchs I went through didn't help much.
I have an article page with a "comment" form that I want to send to my "comment" table. The "comment" table has joins with my "user" and "article" tables (to get which article the comment is part of, and which user sent it)
My comment table columns : comment_id, article_id, author_id, submitted_at, content
My user table columns :
user_id, username, password
My article table columns : article_id, preview_image, title, description, body, publishedAt, author_id
So this is what my query looks like :
public function setComment() {
try{
$stmt = $this->connection()->prepare("INSERT INTO comment (article_id, author_id, submitted_at, content) (SELECT comment.article_id, comment.author_id, submitted_at, content
FROM comment INNER JOIN user ON comment.author_id = user.user_id INNER JOIN article ON comment.article_id = article.article_id)");
$stmt->bindParam(':article_id', $_GET['id'], PDO::PARAM_INT);
$stmt->bindParam(':author_id', $_GET['id'], PDO::PARAM_INT);
$stmt->bindParam(':content', $_POST['comment'], PDO::PARAM_STR);
$stmt->execute();
} catch (PDOException $e){
echo $e->getMessage();
}
}
Well there is no error.... the only problem here is, when I submit my form all my rows in the comment table are duplicated by 2 lol... I just want to add a new row with the data in my bindParam()
So what's wrong?
BY THE WAY during my searchs I've seen people don't specify VALUE() when inserting to a table that has joins. So how do I insert the data that are in my bindParam()? That's weird
EDIT :: FOUND IT!! Actually I didn't need to use a SELECT at all
The correct query was :
INSERT INTO comment (article_id, author_id, submitted_at, content)
VALUES (:article_id, :author_id, NOW(), :content)
I had an error telling me "SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails"... So I thought I needed to join the tables or something but the actual problem was because in my query I bound the author_id to $_GET['id'] (that was 9)... and there is no user with the id of 9 in my user table. Shame on me
I used $_GET['id'] because I don't know how to properly get the id of the user sending the comment (and bindParam doesn't like it when I just use an integer)... with the session maybe idk, but that's a problem for another time