CODEWITHSUNDEEP
phpglobal
Andy
Andy

Reputation: 11

Php global keyword in different file

I am new to php. I have one file for the connection to database "db_connection.php".

<?php
  //With constants
  define("DB_SERVER","localhost");
  define("DB_USER","root");
  define("DB_PASS","");
  define("DB_NAME","db_name");    
  $connection = mysqli_connect(DB_SERVER, DB_USER, DB_PASS, DB_NAME);
  // Test if connection succeeded
  if(mysqli_connect_errno()) {
    die("Database connection failed: " . 
         mysqli_connect_error() . 
         " (" . mysqli_connect_errno() . ")"
    );
  }
?>

I also have another file called "functions.php".where i have a function for the query

<?php
    function confirm_query($result_set){
        if (!$result_set) {
            die("Database query failed.");
        }
    }

function find_all_subjects(){
    global $connection;
    $query  = "SELECT * ";
    $query .= "FROM subjects ";
    $query .= "WHERE visible = 1 ";
    $query .= "ORDER BY position ASC";
    $subject_set = mysqli_query($connection, $query);
    // Test if there was a query error
    confirm_query($subject_set);
    return $subject_set;
}
?>

The main file where i call the function "main.php"

<?php   require_once("db_connection.php"); ?>
<?php   require_once("functions.php"); ?>
<?php $subject_set = find_all_subjects(); ?>

There is no problem everything works fine but can you explain how global $connection; inside "functions.php" is actually working?

Upvotes: 1

Views: 523

Answers (2)

DocWeird
DocWeird

Reputation: 288

When you include or require PHP files in a webpage, even if you split all your code and functions in separate files, it is essentially the same if you included just one file with all the code from the separate files.

So a variable which you declare / create in "db_connection.php" works the same if you created it in the "functions.php" if you include both files in the same page.

This is why you must be careful with variable, function, etc naming if you use separate files.

Upvotes: 1

Sagar Bhut
Sagar Bhut

Reputation: 657

when you write that line 

<?php   require_once("db_connection.php"); ?>

then that behave like db_connection.php file write in that file.

then other line you write 

<?php   require_once("functions.php"); ?>

then that behave like you write function.php file in main.php file so that work fine..

Upvotes: 0

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