Error caused by mysql_select_db() and variable

[mrcaveman]

I'm trying to log into the database by using, !@mysql_select_db($dbname); This does not work, unless I write the name of the database instead of a variable inside the function. Does anyone know why?!?

Here is my function:

function db_connect()
{
$result = @mysql_connect($SESS_DBHOST, $SESS_DBUSER, $SESS_DBPASS);
	if (!$result)
		return false;
	if (!@mysql_select_db($SESS_DBNAME))
		return false;
   return $result;
}

Kj.

[tomhath]

I doubt the mysql_connect is working the way you think either. Read up on variable scope:

http://www.phpbuilder.com/manual/language.variables.scope.php

Also read up on error checking:

http://www.phpbuilder.com/manual/function.mysql-error.php

[mrcaveman]

This didn't help me very much. How does the mysql_connect work, then?!?

I hope someone could help me, instead of lecture me. When I know what I'm doing wrong, I'll learn and perhaps teach someone else next time.

Helpful for any help I could get, or maybe a suggestion to solve my problem.

Kj.

[tomhath]

I'll try again.

You use variables named $SESS_DBHOST, $SESS_DBUSER, $SESS_DBPASS, and $SESS_DBNAME inside your db_connect function.

I assume (but you never said so) that variables with these names were assigned values somewhere else.

But the variables you set somewhere else are not the same variables inside your function, even if they have the same name!

Try the example in the link I first posted. There are two entirely different variables in this example, both named $a. I suspect that's the problem in your function. All of the $SESS_* variables you are using inside the db_connect function are local variables, not the global variables with the same name that you set somewhere else.

   $a = 1; /* global scope */ 

  Function Test () { 
      echo $a; /* reference to local scope variable */ 
  } 
  Test ();
 

[egmax]

function() <-$SESS_DBHOST, $SESS_DBUSER, $SESS_DBPASS

[mrcaveman]

Hi tomhath.

Thanks for helpful remarks. I guess your right, at least almost.

The file is a config file, witch is included() in all other "pages". The SESS_* is therefore also included in other files, but not as "global $variable;". I have read that using globals is not a good idea, because of security hazards. I try to avoid using globals in my script.

$SESS_DBHOST = 'localhost';	/* database server hostname */

$SESS_DBNAME = 'db_name';	/* database name */
$SESS_DBUSER = 'user';	/* database user */
$SESS_DBPASS = 'password';	/* database password */

$SESS_DBH = 'localhost';

function db_connect()
{
	$result = @mysql_pconnect($SESS_DBHOST, $SESS_DBUSER, $SESS_DBPASS);
		if (!$result)
			return false;
		if (!@mysql_select_db($SESS_DBNAME))
			return false;
   		return $result;
}

My first thought was to write all the variables in the function name like, ... function db_connect($SESS_DBHOST, $SESS_DBUSER, $SESS_DBPASS, $SESS_DBNAME)... . If this is the case (is it??) my guess is that I have to do the same on every page there I call the function.

If this is the only way to solve it, it would be easier to write the host, db_name, username and password in the function instead of using variables.

I'm glad if you could comment my remarks. Thank you anyway for your last reply.

Kj.

[tomhath]

You have confused two (easily confused) things:

global variable scope - What is causing the problem here, this is not a security concern. You can safely use global variables when register_globals is turned off.

register_globals - the security problem you are trying to avoid, where "automatic" global variables can be created from a POST or GET request:

http://www.php.net/manual/en/security.registerglobals.php