PHP mySQL connection problems

Question

Ok, I am completely baffled.

I am setting up an OO site. I have a class that defines all my database params, as follows:

$db->host= "localhost";
$db->name= "mydatabase";
$db->user= "user";
$db->pw = "password";

The class is being instantiated correctly and the values show up in pages that appear after this class has been loaded.

BUT, when I try to connect to this database from a different class, it does not connect. Here's how I am connecting:

$dbconn = mysql_connect($db->host, $db->user, $db->pw);
mysql_select_db($db->name, $dbconn);

Everything works fine if I take out the user, pw and name variables and hard code in the correct values, but if any of them is referenced using the db construct, no connection happens. Again, the db construct appears just fine on other pages and I am seeing the variable values being presented correctly. The $db->host variable, however, always works.

Here's is how I am constructing the db class:

class database {
    var $host;
    var $name;
    var $user;
    var $pw;

    function __construct($host = "localhost", $name = "mydatabase", $user = "user", $pw = "password"){
        $this->host =   $host;
        $this->name =   $name;
        $this->user =   $user;
        $this->pw =     $pw;
    }
}

and then I of course do

 $db = new database();

Thanks in advance for any help!

Your database class only stores uid/password/host/dbname ? Then what's the point of this "class"? — VolkerK
– VolkerK, Commented Aug 27, 2010 at 23:30

Crozin · Accepted Answer · 2010-08-28 01:59:50Z

2

Don't use PHP4
Why don't you just use PDO
What's the point of storing password or username as a object property?
Probably the problem is a $db variable scope

How to fix all of that?

class MyClass {
    protected $db;

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

    public function doSth() {
        $this->db->query('..');
    }
}

$db = new PDO('mysql:dbname=mydatabase;host=localhost', 'user', 'password');
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$obj = new MyClass($db);
$obj->doSth();

edited Aug 28, 2010 at 1:59

answered Aug 27, 2010 at 23:31

Crozin

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2 Comments

Gary Over a year ago

I didn't realize that I was using PHP4 code... thanks for the info!

Gary Over a year ago

FYI... in the code sample above, db_name should be dbname... at least for mySQL anyway. Took me quite a while to figure that out!

anurag-jain · Accepted Answer · 2010-08-28 07:25:54Z

0

I think u are not passing parameters when creating object for initializing the database class constructor.

try using

$db=new database("localhost","dbname","user","password");

and then create the class as

class database {
   var $host;
   var $name;
   var $user;
   var $pw;

       function __construct($host , $name , $user , $pw ){
        $this->host =   $host;
        $this->name =   $name;
        $this->user =   $user;
        $this->pw =     $pw;
    }

Also include this class as file if written separately and for connection u can now write

$conn=mysql_connect($db->host,$db->user,$db->pw);
mysql_select_db($db->name,$conn);

Hope this helped :)

answered Aug 28, 2010 at 7:25

anurag-jain

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Comments

Affix Programmer · Accepted Answer · 2015-08-23 02:32:26Z

<?php
/*
link.php
Created By Nicholas English
*/
$link = null;
$connection = null;
$servername = "";
$username = "";
$dbname = "";
$pass = "";
$mysqli = null;
$pdo = null;
$obj = null;
$pr = null;
$type = 3;
if ($type === 1) {
$mysqli = true;
$pdo = false;
$obj = true;
$pr = false;
} else {
if ($type === 2) {
$mysqli = true;
$pdo = false;
$obj = false;
$pr = true;
} else {
if ($type === 3) {
$mysqli = false;
$pdo = true;
$obj = false;
$pr = false;
} else {
$mysqli = null;
$pdo = null;
$obj = null;
$pr = null;
}
}
}
if ($mysqli === true && $obj === true) {
$link = new mysqli($servername, $username, $pass, $dbname);
if ($link->connect_error) {
die("Connection failed: " . $link->connect_error);
}
$connection = true;
} else {
if ($mysqli === true && $pr === true) {
$link = mysqli_connect($servername, $username, $pass, $dbname);
if (!$link) {
die("Connection failed: " . mysqli_connect_error());
}
$connection = true;
} else {
if ($pdo === true && $mysqli === false) {
try {
$link = new PDO("mysql:host=$servername;dbname=$dbname", $username, $pass);
$link->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$connection = true;
}
catch(PDOException $e)
{
$connection = null;
echo "Connection failed: " . $e->getMessage();
}
} else {
$link = null;
$connection = null;
}
}
}
if ($connection == null && $link == null) {
$error = 1;
}
?>

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