show data in page PHP

Question

I am not able to show the data from DB to page and getting

Notice: Undefined variable: id

This is my code

<?php

            if (isset( $_GET[ 'id' ] ) ) {
                $id = $_GET[ 'id' ];
            }

            $query2 ="select * from video where vid='$id'";
            $sql2 = mysqli_query( $con, $query2 );
            $row2 = mysqli_fetch_assoc( $sql2 );

            ?>

            <iframe src="https://www.youtube.com/embed/<?php echo $row2['link'];?>" height="300" width="400" scrolling="no" frameborder="0"></iframe>
            <h1>
                <?php echo $row2['title'];?>
            </h1>
            <p>
                <?php echo $row2['description'];?>
            </p>

0 ) { while ( $row4 = mysqli_fetch_array( $sql ) ) { ?>

        <div class="comment">
            <p>
                <?php echo $row4['comment'];?>
            </p>
            <p>
                <?php echo "From ". $row4['uid'];?>
            </p>

        </div>
        <?php
        }

        }

        if ( isset( $_POST[ 'submit' ] ) ) {
            if ( empty( $_POST[ 'email' ] ) || empty( $_POST[ 'comment' ] ) ) {

                $erro = "<p class='text-danger'> Fill the Required Fields</p>";


            } else {

                $Commentquery = "insert into comments (vid,uid,status,comments,datetime) values ('$id','$_POST[email]', 'pending','$_POST[comment]',now())";

                if ( mysqli_query( $con, $Commentquery ) ) {

                    $sucess = "<p class='text-sucess'> Thankyou</p>";

                }
            }
        }
        ?>

        <div class="comment_form">
            <h2> Comment on post</h2>

            <?php
            if ( isset( $err ) ) {
                echo $err;
            }
            if ( isset( $sucess ) ) {
                echo $sucess;
            }

            ?>

            <form method="post" action="">
                <div class="form-group">
                    <lable> Email Address</lable>
                    <input type="email" name="email" class="form-control"/>
                </div>
                <div class="form-group">
                    <lable> Comment</lable>
                    <textarea name="comment" class="form-control" cols="40" rows="4"></textarea>
                </div>
                <div class="form-group">
                    <input type="submit" name="submit" class="btn btn-default"/>
                </div>


            </form>

        </div>

Can any one tell me what wrong thing I am doing?

i have updated the code and added the $id = -1; as you told me the error is gone but started getting this error

Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given in C:\wamp64\www\site\admin\post.php on line 41

the line which is -

if ( mysqli_num_rows( $sql ) > 0 ) {
                while ( $row4 = mysqli_fetch_array( $sql ) ) {
                    ?>

you can see it in the code also please let me know why the id is creating the issue

`$id` is inside `if-else` block. put closing bracket of `if-else` `}` at the end — Zain Farooq, Sep 06 '18 at 06:34
Bobby Tables will punish you with a database ownage for your bad SQL query construction practices. http://bobby-tables.com/ (hint: What happens if somebody requests record ```1'); DROP TABLE videos; --```?) — GordonM, Sep 06 '18 at 08:49

Zain Farooq · Answer 1 · 2018-09-06T08:41:49.557

Your all code below if{} is related to $id which is inside if{} and will be executed in any case so put } closing bracket at the end so that the code below if{} will be under if{} and only be executed if your $id is set

if (isset( $_GET[ 'id' ] ) ) {
            $id = $_GET[ 'id' ];
        //removing bracket from here

        $query2 ="select * from video where vid='$id'";
        $sql2 = mysqli_query( $con, $query2 );
        $row2 = mysqli_fetch_assoc( $sql2 );

        ?>

        <iframe src="https://www.youtube.com/embed/<?php echo $row2['link'];?>" height="300" width="400" scrolling="no" frameborder="0"></iframe>
        <h1>
            <?php echo $row2['title'];?>
        </h1>
        <p>
            <?php echo $row2['description'];?>
        </p>
<?php } //adding bracket here
       else
           {
             echo 'id is not set';
           }
 ?>

Rinsad Ahmed · Answer 2 · 2018-09-06T06:41:47.903

1

Well, give an initial value for the id. It will cover the scenario where no id is passed which will prevent from undefined variable error

 $id = -1;
 if (isset( $_GET[ 'id' ] ) ) {
    $id = $_GET[ 'id' ];
 }

Also you should make sure the $row is used only when there is a record so change the rest of the code as follows

$query2 ="select * from video where vid='$id'";
        $sql2 = mysqli_query( $con, $query2 );
        if($row2 = mysqli_fetch_assoc( $sql2 )){

        ?>

        <iframe src="https://www.youtube.com/embed/<?php echo $row2['link'];?>" height="300" width="400" scrolling="no" frameborder="0"></iframe>
        <h1>
            <?php echo $row2['title'];?>
        </h1>
        <p>
            <?php echo $row2['description'];?>
        </p>

    <?php } ?>

edited Sep 06 '18 at 06:41

answered Sep 06 '18 at 06:38

Rinsad Ahmed

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This will probably end up in errors further down as it will fail to find a record (I assume) and the fields associated with the row will be undefined. – Nigel Ren Sep 06 '18 at 06:40
i added the $id = -1; the error is gone but the content is still not coming up like video and its details also the code is not full can you let me know how to post the full code – s singh Sep 06 '18 at 07:05
i think i am able to update the code please check now – s singh Sep 06 '18 at 07:08
well. you should pass index.php?id=1 like that on the browser – Rinsad Ahmed Sep 06 '18 at 08:07
i am getting this Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given in C:\wamp64\www\site\admin\post.php on line 41 – s singh Sep 06 '18 at 08:43
see the first code which i posted i have updated the code – s singh Sep 06 '18 at 09:49
what is this mysqli_num_rows( $sql ) ? $sql is a string. Why do you pass it to mysqli_num_rows. – Rinsad Ahmed Sep 06 '18 at 09:52
to get the comment for the page – s singh Sep 06 '18 at 10:46

show data in page PHP

2 Answers2