Why can't i write my MySQL database using a 'required' function? - php

Question

I'm using a file called "lib.php" in which i have defined many functions.
One of these functions is the following :
function dbconn()
{
$servername="127.0.0.1";
$username="root";
$conn=mysql_connect($servername,$username)or die(mysql_error());
mysql_select_db("profit",$conn) or die(mysql_error());
}
In all the .php pages of my website, i've been using this dbconn() function, and it seemed to work fine for reading information from the database. However, when trying to write information, it seems to pose a problem. Specifically, the following code did not function :
<?php
require ("lib.php");
set_time_limit(60);
session_start();
dbconn();
$sql="update `city` set end_dt=now() where city_id='$_POST[killcity]'";
$result=mysql_query($sql,$conn) or die(mysql_error());
header("Location: manipulate.php");
?>
It says that conn is an undefined variable, whereas it should be defined by dbconn() in lib.php.
So, i've found a way around this, by instead creating a new php file called dbconn.php, which contains the exact same thing as dbconn(), and by inserting require ("dbconn.php"); instead of dbconn();.
But i'm still wondering : why did the original way not work ?

Answer 1

You could add a return statement for the function, through you could use global variable in a function, that's not good practice. If you want to, see how global variable works.
function dbconn() {
$servername="127.0.0.1";
$username="root";
$conn=mysql_connect($servername,$username)or die(mysql_error());
mysql_select_db("profit",$conn) or die(mysql_error());
return $conn;
}
$conn = dbconn();