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So i am fairly new to PHP and have few questions. So i have a main index page that includes a header page and a functions page. In the body of the index page, I call a few functions.

In my header include, i have my DB connection which loads with the index page. In each of my functions, i was NOT calling a new db connect because I figured that the db connection in the header would stay open while my functions ran. Well even though the db connection is opened in the header, I am getting an error message (db connection failed) when calling a function that required db access.

So I added a db connection to each of my functions and it works fine. My question is, I am opening a database connect when the page loads via the header. Then im opening another connection when each function is called which could be 3-5 more db connection calls on this page.

This doesn't seem efficient to me. Is this the correct way (calling a connect inside each function) or is there a solution/best practice so that I am only opening one db connect per page regardless of the number of functions called? Again when i remove the connection from the function itself, i get a fail. My connection function looks as follows:

function wm_connectToDatabase () {
    $dbhost = "xxx";
    $dbuser = "xxx";
    $dbpass = "xxx";
    $dbname = "xxx";
    $dbconnection = mysqli_connect($dbhost, $dbuser, $dbpass, $dbname);
    if(mysqli_connect_errno()){
        die("Connection Failed: ". mysqli_connect_error() ."(". mysqli_connect_errno() .")");
    } else {
        echo "</br>Connection Success</br>";
    }
    return $dbconnection;
}

So my header calls this function when index loads. Then each of my functions call it again like this:

function fctn1($table){
    $db = wm_connectToDatabase ();
    ...function stuff here...
}
function fctn2($table){
    $db = wm_connectToDatabase ();
    ...function stuff here...
}

Initially i assumed that the header connection would suffice for all functions so long as the functions were called on a page that had a connection in the header but I found out this is not the case. My functions only work if im opening another connection inside each function as well. I am not sure why the initial connection in the header doesn't stay open to the functions in the body of my page? Thank you for any help.

Again, when i remove the db connection from the functions, the functions "fail" as if there is no db connection even though im calling the connection in the header. Thanks.

user982853
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2 Answers2

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You are dealing with Variable Scope.

Inside a PHP function, no references to the "outside world" exist.

$bar = 'foo';

function sayThis() {

    echo $bar;   // $bar is empty/uninitialized, prints nothing
}

function sayItReally() {

    global $bar; // tell PHP you plan to reference the outside world
    echo $bar; // this will work
}

However, this is a broad subject and this simplified example only serves to break the ice and solve your immediate issue. You really should read about Scope, because this can bite you in many more places besides your DB connections ...

Kevin_Kinsey
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0

Your connection isn't keeping because the $dbconnection variable isn't being passed to your other functions.

You'll need to do something like this in your header:

$db = wm_connectToDatabase ();

Then in your other functions, modify them so they take the database connection you've already made:

fctn1($table, $db);

You can also use global variables like so:

function fctn1($table){
     global $db;
}
Oliwol
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  • Ok that seemed to work. Is there any services out there that will tell you how many time your page connects to the internet or how many queries are ran? Similar to a pingdom for page load times? Just want to make sure my page and globals are working right. Thanks. – user982853 May 09 '17 at 17:17