Use mysql query in a function error

[underv3]

I'm not sure if that is the problem but I am getting this error:

Warning: mysql_query(): supplied argument is not a valid MySQL-Link resource in /------------/example.php on line 124

 

The code is:

function read(){ 
mysql_query("UPDATE table SET on = '1' WHERE id = $idstatus", $connection) or die("Error querying database. Please contact the webmaster about this issue.");
header('Location: example.php');
} 

 

This is for one of the functions (the one that I am calling) the rest are just there for now but I am assuming that they don't matter if you don't call them.

 

I essentially want to set the field "on" to 1 only where the id matches the selected "idstatus".

 

Any help would be great!

 

Thanks!

 

[Jeremysr]

You can't use variables defined outside of your function inside your function, like $connection. You have to make it global like this:

 

function read(){
    global $connection;
    global $idstatus;

    mysql_query("UPDATE table SET on = '1' WHERE id = $idstatus", $connection) or die("Error querying database. Please contact the webmaster about this issue.");
    header('Location: example.php');
}

 

Also you should try to use as few globals as possible. Making your $connection global might be an exception, but you'll probably want to pass your $idstatus as an argument into the function.

[underv3]

Also you should try to use as few globals as possible.

When would it be appropriate?

 

but you'll probably want to pass your $idstatus as an argument into the function.

I'm not really sure how. I found this article giving methods to pass information in and out of functions but i'm not really sure how to incorporate it.

 

Just for the sake of testing my function I put all the variables inside my function and I still get an error  :-\

function read(){ 
$connection = mysql_connect("localhost", "user", "pass") or die("Error connecting to the database. Please contact the webmaster about this issue.");
mysql_query("UPDATE table SET on = '1' WHERE id = 25", $connection) or die("Error querying database. Please contact the webmaster about this issue.");
header('Location: example.php');
} 

 

Would it matter that the "on" field in my database has a default value of "0"?

 

And even with that code I'm getting the die error "Error querying database. Please contact the webmaster about this issue."

???