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I am thinking, is it safe and OK to use db connection in function to return it anywhere in the project? If I want to reuse this project to build another one, I can change db connection only in this function and I don't need to go all over the script searching and changing connection parameter. 

function connect_db(){
$db = new PDO('mysql:host=localhost;dbname=;charset=utf8', '', '');
return $db;
}

Now I can call it anywhere functions.php file is required once, by returning 

$db = connect_db();

and then whatever statement follows.

Is it ok and safe?

And how to close connection like this at the end of the page?

 $db = NULL;

apparently won't work.

Benny Hill
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grab
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1 Answers1

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Yes, it is safe and ok to have a single place that creates a connection to your database. I would change your function just a bit though:

<?php
function connect_db(){
    try{
        return new PDO('mysql:host=localhost;dbname=mydb', 'username', 'password', array(PDO::MYSQL_ATTR_INIT_COMMAND =>'SET NAMES utf8'));
    }catch (PDOException $e){
        echo '<p>Error connecting to database! ' . $e->getMessage() . '</p>';
        die();
    }
}
?>

You can read more about the PDO constructor in the documentation.

And to close the PDO connection created this way you do indeed just:

<?php
$pdo = NULL;
?>

Please note that there is really a lot more to be said on this subject. Ideally you would have a class that handles the creation of your PDO object(s). You might want to take a look at this excellent answer from Gordon as a place to start.

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Benny Hill
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  • for closing connection this variable $pdo isn't defined in function is that a typo? – grab Jan 31 '14 at 14:57
  • @grab My `$pdo` is equivalent to your `$db` - I just used a different variable name, sorry about the confusion. – Benny Hill Jan 31 '14 at 15:06