How to do this?

[NZ_Kiwis]

I've got a database full or records, i have a page where it displays the records in a priority order based on a field "MyPriority" which is a integer.

The issue i have is if more than one user is on the page i don't want the same record to show for both.

How can i get around this?

I've though about having a field called "BeingDisplayed" and have an Ineger set to 1 when it's displayed but how do i reset it back to say 0 (not being displayed) if a user refreshes the page and or closes the browser down after displaying a record.

[johanafm]

You should probably do something like this to keep one user per row

-- update first
UPDATE table SET being_displayed_to = @user_id WHERE being_displayed_to IS NULL LIMIT 1;

-- then select
SELECT ... FROM table WHERE being_displayed_to = @user_id

When the user is done with the row, reset this field to null again.

You will obviously also need to deal with users leaving the row editing page through some other means than submitting the page to your server.
I believe you could deal with this by setting an event handler for window.onunload. But there is still no guarantee that this event will fire. Even if you can require javascript to access the site, a user could still disable javascript after acquiring a row, or the browser could crash. So you should also set a timestamp for when the row was acquired, and then clean set being_displayed_to = null after a certain time has passed.

Aside from this, I'd also recommend not using upper case for identifiers, at least if using mysql on a windows OS, since that is case insensitive. So if you move to another OS (or possibly another DB on windows), you risk introducing errors when the system becomes case sensitive.

[NZ_Kiwis]

Sounds great.
how can i prevent the window.onunload from firing when a user submits the form though?

[NZ_Kiwis]

What about, when one is displayed I set a cookie called OnDisplay with the value $DisplayID

I also update the database with OnDisplay set to 1 and OnDisplayUser set to a $UserID

When a page loads it gets the cookie and resets everything to 0 and resets it later on in the page, this will solve the refresh page issue.

Also set an expiry with another field OnDisplayExpirey and have it set to time() and when the gap between $SavedTime and time() is greater than 180 it sets it back to 0. this will solve the closed page option.

[johanafm]

NZ_Kiwis;10976190 wrote:

Sounds great.
how can i prevent the window.onunload from firing when a user submits the form though?

The order of events is submit click event, form submit event, window unload event. So by using either submit.onclick or form.onsubmit event, you can clear the window.onunload event handler

<script type="text/javascript">
function doClose()
{
	alert ('close');
}
function doSubmit()
{
	alert ('submit');
	/* if form is submitted, clear the unload event handler */
	window.onunload = null;
	return true;
}
function doClick()
{
	alert ('click');
	return true;
}

window.onunload=doClose;

</script>
</head>