Using buttons to loop to the next element from the data fetched from database

[dangar]

I want to have a next button on my Productdetails.php page that would show the next image fetched from the database using while loop. Below is the  productdetails.php  page shows details of a particular product.

I am using simple php format, How can I go about it? I have come this far at this point.

<div class = "uniqueproduct"> 
        <?php 
            if (isset($_GET['id']))
            {
                $id = $_GET['id'];
                $query1 = mysqli_query($conn, "select * from products where PRODUCT_ID = $id");
                while ($row1 = mysqli_fetch_array($query1)) {
        ?>

            <div class = "singleproduct">
            <?php echo '<img src = "data:image/jpeg;base64,'.base64_encode($row1['PRODUCT_IMAGE']).'" alt = "" width = "250px" height ="300px"/>'; ?>
            </div>

            <div class = "productName">
            <?php echo $row1['PRODUCT_NAME']; ?>
            </div>

            <div class = "productDescription">
            <?php echo $row1['PRODUCT_DESCRIPTION'];?>
            </div>

            <div class = "productPrice">
            <?php echo $row1['PRODUCT_PRICE']; ?>
            </div>


            <?php
            }
            }
            ?>


        <button class = "btnPicture"> ..............</button>
    </div>

 

[cyberRobot]

If you're not doing so already, you should look into using prepared statements. You'll want to avoid use the raw GET variable, at least one that's not tested, in a query. Using the raw (untested) value makes the query susceptible to SQL injection attacks, among other issues.

 

Assuming $_GET['id'] should contain a number, you can make sure it does with ctype_digit(). More information can be found here:

http://php.net/manual/en/function.ctype-digit.php

[cyberRobot]

As for your question, I assume that the button will lead to the same productdetails.php page. You could run another query to get the ID for the next record. Then just create a button (or link) to pass the value.

 

Note: MySQL doesn't always return the values the same order. The order it uses doesn't always make sense. For the next-record feature to work, you'll want to look into sorting (ORDER BY clause).

[ginerjm]

You state that you want to use a button to get your next record and that you want to use a while loop.  Uh...  that won't work since your button is on the client and your while loop would be on the server.

 

As indicated above you will display a single record that has a key in it.  Somehow you will need to pass that key back to the server/script and use it to query for the 'next' record, whatever it is.  There would be no loop involved.

[dangar]

Thanks for that, cyberRobot. I've tried this : 

<a href="Productdetails.php?id=$id + 1">Next</a>

shows error. 

[cyberRobot]

PHP variables need to be enclosed with PHP tags. You could try something like the following:

<a href="Productdetails.php?id=<?php echo $id + 1; ?>">Next</a>

Or

<a href="Productdetails.php?id=<?php echo $id++; ?>">Next</a>

Note: you'll want to double check the ID exists before displaying the Next link. 

Edited September 20, 2017 by cyberRobot

[Psycho]

Note: you'll want to double check the ID exists before displaying the Next link. 

 

Correct. There is no guarantee that the next record will be +1. A better solution is to provide the actual ID of the next record. Use a query such as this:

 

SELECT * FROM table WHERE id >= [passed_id] ORDER BY id LIMIT 2

Use a 0 for the first request to start the process. Then use the first record to display the current record. If a 2nd record is returned, use its id in the link/button to get the next record. If no second record is returned, then don't provide a link/button for the next record.

[cyberRobot]

Correct. There is no guarantee that the next record will be +1. A better solution is to provide the actual ID of the next record. Use a query such as this:

SELECT * FROM table WHERE id >= [passed_id] ORDER BY id LIMIT 2

 

Good point. I was only thinking about the last record. There's a good chance that there will be gaps in the middle, eventually.