这种MySQL语法很糟糕，有时可以工作，有时却不能……（严重）

Question

Check this out:

if (isset($_POST['username'])) { 
    $username = $_POST['username'];
}

$connect = mysql_connect("localhost", "root", "");
mysql_select_db("TagDB");

$query = mysql_query("UPDATE friendtable SET state = '1' 
    WHERE (userB = '$username' AND state = '0')");

This should simply update a table to show a state of 1 for every instance the userB column consists of the posted username. However, this only works sometimes. Without changing any code whatsoever, this method will sometimes to as it ought to, and other times do nothing. Strange.

if (isset($_POST['state'])) {
    $state = $_POST['state'];
}

if (isset($_POST['username'])) {
    $username = $_POST['username'];
}

if (isset($_POST['frienduser'])) {
    $frienduser = $_POST['frienduser'];
}

$connect = mysql_connect("localhost", "root", "");
mysql_select_db("TagDB");

$query = mysql_query("UPDATE friendtable SET state = '$state' WHERE (userA = '$frienduser' AND userB = '$username')");

This does the same. Sometimes its perfect, other times, no change. I have no idea what could be different. My only lead is that I sometimes manually change values in MySQL via phpmyadmin to test some stuff. Could it be getting confused because I'm putting in some values manually? I wouldn't think so, but its the only lead I have. Take a look at the code and see if you can spot anything that would cause this strange issue, if you have the time. Thank you.

Answer 1

I'm a complete idiot. I'm posting this as an answer to help anyone who may run into this problem too. Basically, I would change the state to 0 to check if various inputs worked. I'd then refresh the page to see if the state had changed after I had made an input. However, when refreshing the page it refreshed my previous mysql request.... to set the state to 0. So by refreshing I was really undoing what I had just done. Sorry to bother you all with this, but hopefully this post will serve someone else in the future. Thanks!