How to compare two columns from diffrent tables

Question

Hi :) I write some code for me and I need to compare two columns from different tables.

I have table blog_posts with postID and I have table blog_comment with also have postID.

I write something like this for start:

<?php
$stmt2 = $db->prepare('SELECT comment_sender_name, comment_date, comment 
                       FROM blog_posts, blog_comment 
                       WHERE blog_posts.psotID = blog_comment.postID');
$stmt2->execute(array(
    ':comment_sender_name' => $comment_sender_name,
    ':comment_date' => $comment_date,
    ':comment' => $comment
));
if ($row['blog_posts.psotID'] == $row['blog_comment.postID']) {
    echo '<p>' . $comment_sender_name . '</p>';
    echo '<p>' . $comment_date . '</p>';
    echo '<p>' . $comment . '</p>';
} else ($row['blog_posts.psotID'] == '') {
    header('Location: ./');
    exit;
}
?>

And this is the error I get :

Parse error: syntax error, unexpected '{' in /home/pomarex1/domains/dev.automax-rent.eu/public_html/comments-loop.php on line 12

And what doesn't works? What is your error? What is the desired output? — Mickaël Leger, Jun 22 '18 at 12:55
Parse error: syntax error, unexpected '{' in /home/pomarex1/domains/dev.automax-rent.eu/public_html/comments-loop.php on line 12 — Patryk Tchórzewski, Jun 22 '18 at 12:56
I edit your question with your error, but still no idea what you want and this error is clear : check your line 12, you have an unexpected `{` — Mickaël Leger, Jun 22 '18 at 12:58
Your else is wrong, you need to use elseif. Also theres a typo - psotID — Eakethet, Jun 22 '18 at 13:00
Change `} else ($row['blog_posts.psotID'] == '') {` to `} elseif ($row['blog_posts.psotID'] == '') {` ... you are trying to check another condition but you need to use elseif to do it there. — Dave, Jun 22 '18 at 13:01
Your PDO query is wrong btw, you're preparing selected columns and please note that the `:` must be in the query, not the preparation array keys. — AymDev, Jun 22 '18 at 13:01

score 0 · Answer 1 · answered Jun 22 '18 at 13:13

0

I can see two errors in your code (if this is not a typo one):-

In the query where you have written "WHERE blog_posts.psotID = blog_comment.postID" , it should be "blog_posts.postID" and not "blog_posts.psotID" because psotID is not a field in your table .
Like what others say , your else is wrong , either you write

else{ header('Location: ./'); exit; }

OR

else if($row['blog_posts.psotID'] == ''){
    header('Location: ./');
    exit;
}

And thirdly , I will suggest to write an inner join query rather than calling the data directly .

answered Jun 22 '18 at 13:13

PHP Web

257
3
8

thx mate :) 1. I change this ;) 2. I change to elseif 3. I must read about join :) – Patryk Tchórzewski Jun 22 '18 at 13:54
I can write it down for you if your problem is resolved after making the changes . – PHP Web Jun 22 '18 at 14:02

score 0 · Answer 2 · answered Jun 22 '18 at 13:17

This is the code to fetch data from two different tables and you can compare them. Here I've used PDO method

<?php
    require_once('init.php');
    $con = $db->prepare("SELECT * FROM blog_posts");
    $con->execute();
    $con2 = $db->prepare("SELECT * FROM blog_comment");
    $con2->execute();
    while(($post_row = $con->fetch(PDO::FETCH_ASSOC)) && ($comment_row = $con2->fetch(PDO::FETCH_ASSOC))){
            if($post_row['postID'] == $comment_row['postID']){
                echo $post_row['postID'];
        }
    }

?>

Yep but in this code always return first id in column not real postid :) — Patryk Tchórzewski, Jun 22 '18 at 13:52

How to compare two columns from diffrent tables

2 Answers2