如何强制浏览器读取更新的数据库信息？

Question

Apologies if this question has been answered before, but I'm not sure how to easily describe it...

I'm programming a system with PHP and MySql that will allow users that are logged in to build a sports team. I have system set up where a user "bids" on a player, and that player is added to their roster. The code that writes to the database is very simple and works fine:

mysql_query("UPDATE bidpool SET BidExpires='$newbidexpires' WHERE Player='$player'");
mysql_query("UPDATE bidpool SET CurrentBid='$bid' WHERE Player='$player'");
mysql_query("UPDATE bidpool SET TeamName='$NewTeamName' WHERE Player='$player'");

When I check the database, that information is entered correctly.

When I load up another page, where the team's updated roster is located, this is the code I use:

echo "<table>";
$result = mysql_query("SELECT * FROM bidpool WHERE TeamName='$teamname'");

$playerbid = 0;
$i = 0;

$num = mysql_numrows($result);

while ($i < $num) {

    $playerroster = mysql_result($result, $i, "Player");
    $playerbid = mysql_result($result, $i, "CurrentBid");
    $playerexpires = mysql_result($result, $i, "BidExpires");

    IF ($time > $playerexpires) {

        $playerexpires = "BID WON";
    }

    echo "<tr> 
                    <td width='30%'>$playerroster</td>
                    <td width='30%'>$playerbid</td>
                    <td width='30%'>$playerexpires</td>
                    </tr>";
    $i++;
}
echo "</table">;

The problem? Everything writes to the database just fine when there is a new bid. When I load the roster page up in Firefox, it shows the roster as it is in the database, with even the most recent changes shown only seconds later.

When I load it in Safari and Chrome, however, it shows an old version of the roster. Even after I clear the browser cache, reset the browser, and even reboot my computer, it still shows an old version from the database.

This type of system, with multiple users bidding on players over the course of several days, requires that players see the most recent bids and their recent roster changes as soon as possible. But it won't work if the browser won't cooperate.

If it makes any difference, the site is run on WordPress.

What do you think I'm doing wrong here? Why does this system work flawlessly in one browser, but not another?

Thanks a bunch.

Answer 1

The problem is certainly a caching problem; you can test whether it's a client or Wordpress issue by inserting some extra URL parameters.

Try hitting the page with ?extraRandomParameter=changeThisValueEachTime.

If that works, it's a client thing; otherwise, you'll have to investigate more specifically as to how Wordpress caches (and how to get around it).