external database query works in sidebar, not on posts

I wrote a plugin with some functions to query an external database with read-only access. One function executes a query and returns results specified in the args to my sidebar widgets. Works great:

function query($category,$imgsize,$numberofimgs) {
	$j = 0;
	while ( $j < $numberofimgs) {
		include 'config.php';
		$db_server = mysql_connect($host, $user, $pass);
			if (!$db_server) die("Unable to connect to database: " . mysql_error());
			mysql_select_db($database) or die("Unable to select database: " . mysql_error());
		$query = "SELECT * FROM {$category} ORDER BY RAND()";
		$result = mysql_query($query,$db_server);
		$row_cnt = mysql_num_rows($result);
		$row = mysql_fetch_row($result);
				echo "{$row[0]} of {$category} size={$imgsize}"; // etc…
		$j++;
	}
	mysql_close($db_server);
}

This returns a specific output to the sidebar for the browser

Now, I wrote another function that only executes the mysql_select_db() portion of the above, with no args, simply to connect to the database so I can do whatever I needed with the data in posts. This function fails to connect, but is exactly the same method as the above function:

function get_stuff() {
	include 'config.php';
	global $db_server;
	$db_server = mysql_connect($host, $user, $pass);
		if (!$db_server) die("Unable to connect to database: " . mysql_error());
		mysql_select_db($database) or die("Unable to select  database: " . mysql_error());
}

When I call get_stuff() in a post and preview it, it comes back with “Unable to connect to database: “. I even published the post, but again, “Unable to connect to database: “. How is it that one function can connect successfully and execute for sidebar widgets and unsuccessfully for posts?