大型不构成所有元素

I have a dynamically built form with ~900 check boxes in one case, and only ~755 of them are being passed to my processing page.

(Reducing the size of the form isn't an option. It's a schedule matrix with employee down the left and shifts across the top.)

My processing code is

foreach ($_POST as $key => $value){
  $keys=explode("-",$key);
  if(!mysql_query("UPDATE week_schedule SET $keys[1]='$value' WHERE userid='$keys[0]'")){
    echo "<p>".$key." was not updated!</p>";
    $error=TRUE;
  }
}

PLEASE HELP

What is max_post_size (http://ua1.php.net/ini.core#ini.post-max-size) in your server php.ini, perhaps you could run over it. Also, according to php manual than $_POST should be empty, but it worth checking anyway.

Also try to submit form using another browser to be sure that this problem is not browser-specific.

Also script may run out of max_execution_time while doing ≈900 database update queries.

P.S. I see from comment to the question that only ≈750 fields are passing, so maybe there is some naming issue in your form and you have some checkboxes with the same names?