CODEWITHSUNDEEP
phpmysqloopfunctionobject
user1627985
user1627985

Reputation: 87

PHP: PDO global database variable?

i've been coding php for quite a while now but i recently got into object oriented programming.

Before i used mysql_connect(),mysql_query() and all those functions but then i heard that PDO would be way better alternative.

I thought why not and watched a basic PDO video.

try {
    global $db;
    $db = new PDO("mysql:host=$db_host;dbname=$db_name", $db_user, $db_pw);
} catch (PDOException $e) {
    die("ERROR: " . $e->getMessage());
}

print(gettype($db)."<br>");

function test() {
print(gettype($db));
}

test();

So the problem here is, i want to create a function so i can easily insert new items into my table. But i ran to this problem, my $db is not global. So i would have to re-connect to my database when using the function, but i can't do that, it would not be good at all.

So how can work around this problem? Oh and the above code outputs:

object
Notice: Undefined variable: db in /home/vhosts/ollie.ceify.net/www/ip-bless/connect.php on line 25 NULL

Upvotes: 4

Views: 5039

Answers (4)

smithbh
smithbh

Reputation: 347

Create a on object that holds a private PDO Object and define a public query method that accepts table name, column name, and value arguments and can be called repeatedly:

class DatabaseObject{
  private $db;

  public function __construct() {
    $this->createDB();
  }

  private function createDB() {
    $this->db = PDO("mysql:host=localhost;dbname=yourdatabase", 'username', 'password');
        $this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
  }

  public function insert($table, $column, $value) {
    try {
      $this->db->query(sprintf("
        INSERT INTO %s (%s)
        VALUES (%s)",
        $table, $column, $value));
    }
    catch (PDOException $e) {
      return $e->getMessage();
    }
  }
}

$db = new DatabaseObject();
$db->insert('table_name', 'column_name', 'value');

Upvotes: 3

user1598585
user1598585

Reputation:

What I normally do is defining a function for connecting to the database or getting the already available handle.

function dbHandle()
{
    global $dbh;
    if (is_resource($dbh)) return $dbh;
    return $dbh = new PDO(...); # All your DB credentials here.
}

...as a simple example, if you have a more complicated setup you can, for example, store this information in static members of a class.

Upvotes: 0

Matt
Matt

Reputation: 7040

Pass the variable to your function as a parameter.

function test($dbObj) {
    print(gettype($dbObj));
}

OR

You can place your functions inside an object and have $db as a member variable:

class myClass {
    public $db;

    public function __construct($dbObj) {
        $this->db = $db;
    }

    public function test() {
        print(gettype($this->db));
    }
}

$myVar = new myClass();
$myVar->test();

Upvotes: 1

xdazz
xdazz

Reputation: 160833

You need use global to get the global variable too.

function test() {
  global $db;
  print(gettype($db));
}

Upvotes: 1

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