Question

I am a Junior PHP/MySQL Developer and need some help, how do I display front-end menu items by custom sorting using a text field through backend, I want to sort pages(Menut Title) by numbers like 1,2,3 …etc. in front end. It will be too better if I could understand dropdown menu sorting also from your answer. 😀 But anyway Here is my backend code but it is not working I think there needs an array which I am not understanding well:

<form name="sort_form" method="post" action="" >
<?php while($row = mysql_fetch_assoc($res)) { ?>
<tr>
    <input type="hidden" value="<?php echo $row['id']; ?>" name="id" />
    <td><input type="text" value="<?php echo $row['sort_by']; ?>" name="sort_by" size="2" maxlength="2"/></td>
    <td><?php echo $row['page_title']; ?></td>
</tr>
    <?php } ?>
<tr>
    <td colspan="2" align="center"><input type="submit" name="submit" value="Sort" /></td>
</tr>
</form>

And here is the code for when action is performed.

<?php
if(isset($_POST['submit']) == "Sort") {

    $id = intval($_POST['id']);
    $sort_by = intval($_POST['sort_by']);

    $query_update = "UPDATE `pages` SET `sort_by`='$sort_by' WHERE `id`='$id'";
    $updated = mysql_query($query_update) or die ("Update failed!");

    echo "Updated Successfuly!";

}
?>

Hope you understand!

Thanks

Answer 1

To sort the list you can not just update the sort_by field.

If your table has the following data

id  page_title  sort_by
1   title_1         1
2   title_2         2
3   title_3         3

What would happend if you update row 3 with a sort_by value of 1? There will be two rows that have a sort_by value of 1, which one comes first? What happends if you again update row 2 with a sort_by value of 1… there can be a lot of collisions in the sort_by field.

However, there are several ways to get around this. One would be to simply swap sort_by values. So, when you update row 3 to a sort_by value of 1, you will also check if any sort_by values of 1 exists, and if they do, replace them with whatever row 3’s sort_by value is.

If swapping is not the behavior your looking for you can give the sort_by field a float data type. In this case everytime you insert or move something around in your table its sort_by field will be the average of the 2 rows it is sandwiched between. If you wanted to move row 3 between rows 1 & 2 you would set row 3’s sort_by value to 1.5.

id  page_title  sort_by
1   title_1         1
2   title_2         2
3   title_3         1.5

Then if you wanted to move 2 back inbetween 1 and 3 you would set 2’s sort_by value to 1.25

id  page_title  sort_by
1   title_1         1
2   title_2         1.25
3   title_3         1.5

you can continue to do this for a very long time. However, since you are editing your sort by field with a textfield this does not appear to be the right choice for you.

What I suggest is having another column in your table called “sort_by_updated_at”. Everytime you update your sort_by values set sort_by_updated_at to the current time. This way you can sort on two columns. You sort on your regular sort_by field but if there is any collisons you look at the sort_by_updated_at field and whichever row has a lower sort_by_updated_at value will precede all others.