Question

I have a column called list which is used in my order by (in MYSQL queries) and within list is numbers: (e.g. 1 to 20)

This list is then output using MYSQL order by list ASC – However, when I update my list in backend using a Jquery drag drop UI list it is supposed to update the list frontend.

My problem is that my list order sometimes conflicts with other rows as there could be two or three rows with the value of 1 in list therefore when my order updates I would like to know how I can update other rows by +1 only if the rows are >= the order number given

I do not want to make the column primary as I am not aiming to make the list column unique, the reason for this is because there is more than one category – and in each category they all start at 1 – therefore if I make it unique it would cause errors because there was multiple 1’s over different categories.

I asked a friend who said I could probably try PL/SQL using a trigger function but this is new grounds to me – I don’t fully understand that language and was wondering if anyone could help me do what I am trying to using MYSQL or even PL/SQL.

This is what I have so far:

<?php
$project = mysql_real_escape_string(stripslashes($_POST['pid']));
$category = mysql_real_escape_string(stripslashes($_POST['cat']));
$order = mysql_real_escape_string(stripslashes($_POST['order']));
// need to do update the moved result (list row) and update all conflicting rows by 1
mysql_query("UPDATE `projects` SET `cat`='$category',`list`='$order' WHERE `id`='$project'")or die(mysql_query());
?>

Conclusion:

I am trying to update a none unique column to have unique values for that individual category. I am not sure how to update all the rows in that category by +1

Answer 1

@andrewsi is right, in particular I suggest order by list ASC, last_update DESC so in the same query where you update list you can timestamp last_update and therefore you will have not need to use triggers or any other updates.