Connect to database with PDO using a custom function

Question

I have a function called: table().

I can't connect to the database by PDO if I've written the PDO connection outside of the function, like this:

include_once("server.inc");
$connect = new PDO('mysql:host='.$servername.'; dbname='.$db.';charset=utf8' , $username, $password); 
function table()
{
    $sql="select * FROM d1" ;
    $result = $connect->query($sql) ; 
    foreach ($result as $rows ) 
    {
        echo  $rows["Course_name"] . "<br/>" ;
    }
}
echo  table() ;

This code does not work and gives these errors:

Notice: Undefined variable: connect

Fatal error: Call to a member function query() on a non-object

Now if I use the code like this:

function table()
{
    include_once("server.inc");
    $connect = new PDO('mysql:host='.$servername.'; dbname='.$db.';charset=utf8' , $username, $password); 
    $sql="select * FROM d1" ;
    $result = $connect->query($sql) ; 
    foreach ($result as $rows ) 
    {
        echo  $rows["Course_name"] . "<br/>" ;
    }
}
echo  table() ;

everything will be alright, but another problem will happen -- I can only use function table() once! If I use it a second time, this error will happen:

Notice: Undefined variable: servername

Notice: Undefined variable: db

Notice: Undefined variable: username

Notice: Undefined variable: password

Warning: Invalid argument supplied for foreach()

What shall I do to use my function more than once without errors?

Answer 1

You can inject the PDO instance to the function:

include_once("server.inc");
$connect = new PDO('mysql:host='.$servername.'; dbname='.$db.';charset=utf8' , $username, $password); 

function table($connect)
{
    $sql="select * FROM d1" ;
    $result = $connect->query($sql) ; 
    foreach ($result as $rows ) 
    {
        echo  $rows["Course_name"] . "<br/>" ;
    }
}
//echo  table() ;
// Thanks barmar, missed the param before editing!
table($connect); // there's no need to echo the function as it does not return any value, 
                 // the function does the echoing

Oh, and you should read the scoping of variables, and also the include vs. include_once