duplicate record problems

[adunphy]

I have a full php / mysql website going. The trouble is, if a person hits refresh or back on certain pages the data gets duplicated in the database. I have a unique key auto-inc field. I put a unique index on the other fields in the db but its still allowing the record to insert. Does anyone have any ideas to proof for this problem? I thought about selecting from the db before every insert but that seems like a lot of useless db hitting.

Thanks for ANY ideas!

Amy

[ahundiak]

Better recheck your indexes and make sure they were created with the UNIQUE keyword. The only practical way to prevent dup records is by using unique indexes. And they do work.

Maybe you can post an example of your sql index command.

[nemonoman]

I had the same problem. No-cache header directives helped, but some users went through the pain of forcing a refresh despite the warnings.

Here's how I manage it now:

I create a table that delivers a uniqueid called postingflag;

CREATE TABLE postingflag (
id int(11) unsigned NOT NULL auto_increment,
PRIMARY KEY (id)
) TYPE=MyISAM

I created this function:
function postingflag(){
mysql_query("INSERT INTO postingflag VALUES(0)");
return mysql_insert_id();

}

I make my form:
<form action=sumbit.php method=post>
<? $postingflag=postingflag();
echo "
<input type=hidden name=postingflag value=$postingflag>";?>

..and then the rest of the form:

in the submit method I use this code:

<?
$result=mysql_query("SELECT id FROM postingflag WHERE id=$postingflag");
$row=mysql_fetch_array($result);
if($row[0]){
//manage the submit database stuff here;
//once it's done:

mysql_query("DELETE FROM postingflag WHERE id=$postingflag");
}
else{
//the postingflag was deleted, don't repost this data:
die("This form has already been saved");
}