PHP undefined variable mysqli connection

Question

I have a mysql connection which is included in a separate file:

require 'settings.php';

and I have a file with all functions, also included:

require 'functions.php';

In the settings there it looks like this:

$db = mysqli_connect("host", "username", "passwort", "database");
    if(!$db) {
        exit("Error: ".mysqli_connect_error());
    }

and a function uses this connection like this:

function includehomepage() {
            $data = array();
            $query = "SELECT pagecontent FROM `pages` WHERE `id` = `0`";
            $query = mysqli_query($db, $query);
            $data = mysqli_fetch_assoc($query);
            return $data['pagecontent'];
        }

But I get an error message like this:

Undefined variable: db in /var/... on line 18

Do you have an answer? The variable have to be defined in the included file.. I am confused. Thanks for your answers!

In a function there's no $db variable unless u pass it as a parameter or declare as global. — u_mulder
– u_mulder, Commented Sep 23, 2014 at 11:49

Community · Accepted Answer · 2023-11-17 20:24:57Z

4

Variable scope problem. Look at global

function includehomepage() {
   global $db;
   $data = array();
   $query = "SELECT pagecontent FROM `pages` WHERE `id` = '0'";
   $query = mysqli_query($db, $query);
   $data = mysqli_fetch_assoc($query);
   return $data['pagecontent'];
}

edited Nov 17, 2023 at 20:24

CommunityBot

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answered Sep 23, 2014 at 11:50

ʰᵈˑ

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4 Comments

fredkid Over a year ago

thank you! now there is just one more error: Warning: mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, boolean given in ..

ʰᵈˑ Over a year ago

Altered answer. Dont quote the 0 in "<backtick>". It'll think 0 is a column name, and kill the query. [Err] 1054 - Unknown column '0' in 'where clause'. Quote strings in ', or ".

ʰᵈˑ Over a year ago

You're welcome @fredkid. How this site works is to accept an answer once it's successfully answered your question, to "close" your question and to inform others what worked best for you. Both answers here are correct, please accept either one. :)

maxhb Over a year ago

Please avoid using global vars. Use function includehomepage($db) {...} instead!

Mithun Satheesh · Accepted Answer · 2014-09-23 11:56:42Z

2

$db is a global variable to includehomepage function. If you want to access it, then you have to pass it to the function or declare it as global inside the function.

like

function includehomepage() {
     global $db;   
     $data = array();
     $query = "SELECT pagecontent FROM `pages` WHERE `id` = '0'";
     $query = mysqli_query($db, $query);
     $data = mysqli_fetch_assoc($query);
     return $data['pagecontent'];
}

or have it as a parameter in your function and pass it via call.

function includehomepage($db) {
     $data = array();
     $query = "SELECT pagecontent FROM `pages` WHERE `id` = '0'";
     $query = mysqli_query($db, $query);
     $data = mysqli_fetch_assoc($query);
     return $data['pagecontent'];
}
includehomepage($db);

edited Sep 23, 2014 at 11:56

answered Sep 23, 2014 at 11:50

Mithun Satheesh

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