Jump to content

serious connection problems

cubx

By cubx
in PHP Coding Help

Recommended Posts

cubx Newbie

cubx

Posted
Posted
I'm using php 5.2 and mysql 5.1 on my fedora 5 server. Apache 2 and the mysql daemons are both running fine. But I am having constant problems getting php to connect to the mysql daemon on the same machine. It was working very briefly, then it stopped. I cannot find any errors that tell me much.

Here is the entire code:

<HTML>
<HEAD>
<TITLE>New Document</TITLE>
</HEAD>
<BODY>

<?php

// Have the username and password been filled out

function form(){
        echo "<table width=\"100%\" height=\"5%\" bgcolor=\"cyan\">";
        echo "<tr>";
        echo "<td bgcolor=\"white\" width=\"20%\"><font color=\"green\">&nbsp;&nbsp;&nbsp;<font size=+1><b>Step 1</b></font></td>";
        echo "<td>&nbsp;&nbsp;&nbsp;<font size=+1 color=\"white\"><b>Step 2</b></font></td>";
        echo "<td>&nbsp;&nbsp;&nbsp;<font size=+1 color=\"white\"><b>Step 3</b></font></td>";
        echo "<td>&nbsp;&nbsp;&nbsp;<font size=+1 color=\"white\"><b>Step 4</b></font></td>";
        echo "<td>&nbsp;&nbsp;&nbsp;<font size=+1 color=\"white\"><b>Step 5</b></font></td>";
        echo "</tr>";
        echo "<tr bgcolor=\"white\">";
        echo "<td bgcolor=\"red\" width=\"20%\">&nbsp;&nbsp;&nbsp;<b><i><font size=+1>LOG IN</i></b></td>";
        echo "<td></td>";
        echo "<td></td>";
        echo "<td></td>";
        echo "<td></td>";
        echo "</tr>";
        echo "</table>";

        echo "<br><br><br><br><br><br><br><br><br><center>";
        echo "<table border=\"0\" bgcolor=\"#66ccff\" cellpadding=\"10\">";
        echo "<form action='" .$_SERVER['PHP_SELF'] ."' method='post'>";
        echo "<tr><td>What username do you want?</td><td><input type='text' name='username'></td>";
        echo "<tr><td>Pick a password (5-15 characters):</td><td><input type='password' name='password'></td>";
        echo "<tr><td colspan=2 align=center><br><input type='image' name='Submit' value='Submit' src='submit.gif'>";
        echo "</form>";
        echo "</table></center>";
}
       
function connect_to_db() {
    $link = mysql_connect('localhost', 'root', 'rootpassword');
    if (!$link) {
        die('Could not connect: ' . mysql_error());
        }
        else
    $db_selected = mysql_select_db('mydb', $link) or die(mysql_error());
    if (!$db_selected) {
        echo "Cannot use database<br>";
        echo "mysql_error()";
        }
        else
        return TRUE;
}

//function checklength($string, $min, $max) {
//  $length = strlen ($string);
//  if (($length < $min) || ($length > $max)) {
//    return FALSE; // too short or long
//  } else {
//    return TRUE;
//  }
//}

if (!isset($_POST['Submit']))
    form();
else
  while (connect_to_db())
  if (!empty($_POST['username']) && !empty($_POST['password']))
//      if(!checklength($_POST['password'], 5, 15)
//        echo "Password must be between 5-15 characters";

  // Query the database
  $sql = "SELECT username FROM accounts WHERE username = '{$_POST['username']}'";

  // Check if we got a result returned
  $result = mysql_query($sql);
  if (!$result){
      echo "Couldn't execute: $sql<br><br>\n" . mysql_error();
  }
  else {
  // Does the user exist, how many rows were retrurned
      if (mysql_num_rows($result) > 0){
        echo "Username already in use\n";
      }
      else {
        echo "Username doesn't exist\n";
      }
      echo "here is the form";
}

?>

</BODY>
</HTML>

When I pull up the IP address in Firefox, I get this BEFORE I even type anything into the fields:

Warning: mysql_query() [function.mysql-query]: Access denied for user 'daemon'@'localhost' (using password: NO) in /home/www/public_html/form2.php on line 75

Warning: mysql_query() [function.mysql-query]: A link to the server could not be established in /home/www/public_html/form2.php on line 75
Couldn't execute:

Access denied for user 'daemon'@'localhost' (using password: NO)


I go ahead and type in a username and password, then get a blank screen. The database username is root, and it has worked before. But what I don't understand is why I get the error that the server connection could not be established, when the connect_to_db() isn't giving me an error.

Mysql loads and reads the database just fine from the command line.

Any suggestions on what to look for?
Link to comment
https://forums.phpfreaks.com/topic/29356-serious-connection-problems/
Share on other sites
btherl Member

btherl

Posted
Posted
Try specifying the link identifier with each mysql_query() call.  It sounds like you are triggering a new database connection when you don't specify it.

[code=php:0]mysql_query($sql, $link);[/code]


You'll also need to make $link global.  Add [code=php:0]global $link;[/code] in connect_to_db(), and inside each function that you use $link in.
cubx Newbie

cubx

Posted
  • Author
Posted
I made these changes:

function connect_to_db() {
    global $link;

... rest of function code is the same ...

if (!isset($_POST['Submit']))
    form();
else
  while (connect_to_db())
  if (!empty($_POST['username']) && !empty($_POST['password']))
//      if(!checklength($_POST['password'], 5, 15)
//        echo "Password must be between 5-15 characters";

  // Query the database
  $sql = "SELECT username FROM accounts WHERE username = '{$_POST['username']}'";

  // Check if we got a result returned
  $result = mysql_query($sql, $link);
  if (!$result){
      echo "Couldn't execute: $sql<br><br>\n" . mysql_error();
  }
  else {
  // Does the user exist, how many rows were retrurned
      if (mysql_num_rows($result, $link) > 0){
        echo "Username already in use\n";
      }
      else {
        echo "Username doesn't exist\n";
      }
      echo "here is the form";
}

I added the $link to the mysql commands here. Nothing else. The globals variable is inside the connect function only. Now when I reload the page I get:

Warning: mysql_query(): supplied argument is not a valid MySQL-Link resource in /home/www/public_html/form2.php on line 76
Couldn't execute:

And that's all. I thought a global variable had to be outside of a function? It seems to me that the connect is there in the beginning, but as soon as I test usernames or queriers, the connection is dead.
btherl Member

btherl

Posted
Posted
A global variable needs to be specified in every function it is used in.  Other than that, it can be defined anywhere, inside or outside a function.

I'm a bit suspicious about your "while (connect_to_db())" .. what is that intended to do?  Why not just "if (connect_to_db()) { } else { echo "Couldn't connect"; }" ?
cubx Newbie

cubx

Posted
  • Author
Posted
So a global variable MUST be defined inside each function I use it in, it's really not global then, right?

As for the while connected, I did that because I figured that would make sure the database was connected the whole time. Apparently that was the problem. I switched it to an if statement and now it's working.

Very strange, but you were correct.

My last question is when I bring up the form, before I even type in a name, it automatically has "Couldn't execute:" and "Query was empty", which are a little further down in the code. It seems like it is trying to execute those commands before I even hit submit, yet when I hit submit, it does work properly.

Is there a better way I can avoid this?
btherl Member

btherl

Posted
Posted
I think the problem was your while() .. If I include the implicit braces, your code is this:

[code=php:0] while (connect_to_db()) {
  if (!empty($_POST['username']) && !empty($_POST['password'])) {
    // Query the database
    $sql = "SELECT username FROM accounts WHERE username = '{$_POST['username']}'";
  } /* end of if */
} /* end of while */[/code]


What that will do is it will keep connecting to the db and setting $sql UNTIL THE DB CONNECTION FAILS, at which point it will continue.  It should be this:

[code=php:0] while (!connect_to_db());[/code]


That would keep running connect_to_db() until it returns true, then it'll end the loop.

Regarding global variables, they must be [b]specified[/b] in each function they are used in, but they are shared among all functions which specify them.  That's why they are global.

About your second question, I think you are missing braces.  You should do like this:

[code=php:0]if (condition) {
  blah;
  blah;
} else {
  blah;
  blah;
}[/code]
cubx Newbie

cubx

Posted
  • Author
Posted
I changed that while to an if for the connection and that solved the problem. You were right. Man I thought I was fairly good in C.

I get the global variable thing now. Yes I knew what they were, but I had never heard of defining them in each function. That almost sounds like a PHP requirement. As for the code that was executing before submit, I did what you both said, wrapped that section in an if and now it works fine.

Thank you!!

Archived

This topic is now archived and is closed to further replies.

Go to topic listing
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.