Learning mysqli and getting a fatal error..

natdm

I'm just learning PHP and am new to OOP as well. Reading a few books on it and some show mysqli but I understand it's got a procedural method and an OOP method. I try to implement the OOP method in a class but it doesn't work.

<?php
class DB {
    protected $host = '127.0.0.1:3306';
    protected $dbname = 'users';
    protected $username = 'user';
    protected $password = 'pass';

public function connect() {
    $mysqli = new mysqli($this->host, $this->username, $this->password, $this->dbname);

  return true;
}

public function select($table, $where) {
    global $mysqli;
    $query = "SELECT * FROM $table WHERE $where";
    $result = $mysqli->query($query);
    if($result->num_rows == 1)
        return $this->processRowSet($result, true);
    return $this->processRowSet($result);
}

}

?>

And the object:

<?php
//include 'db.class.php';
include 'database_login.php';
$db = new DB();

$db->connect();

$db->select('users.users','id=1');

?>

The error:

Fatal error: Call to a member function query() on a non-object in /Library/WebServer/Documents/tutorial/database_login.php on line 17

Any help would be much appreciated. Maybe talking slowly and using little words, I guess.

If it's needed.. PHP version: 5.5.14

laserlight

$mysqli should probably be a member of the class instead, e.g.,

<?php
class DB {
    protected $host = '127.0.0.1:3306';
    protected $dbname = 'users';
    protected $username = 'user';
    protected $password = 'pass';
    protected $mysqli;

public function connect() {
    $this->mysqli = new mysqli($this->host, $this->username, $this->password, $this->dbname);

    return true;
}

public function select($table, $where) {
    $query = "SELECT * FROM $table WHERE $where";
    $result = $this->mysqli->query($query);
    if($result->num_rows == 1)
        return $this->processRowSet($result, true);
    return $this->processRowSet($result);
}
}

However, note that your select function is arguably too simplistic: when you start to need to use variables as part of the WHERE clause, you would want to use parameter binding with prepared statements instead of just calling $this->mysqli->query. If so, this monolithic $where parameter could prove problematic.

natdm

Thanks! I also had to make another function for ProcessRowSet since I'd skipped over it.

I'm just trying to learn some basics right now. It's not returning an error any more but also not printing anything to the screen. I think I can figure it out.

Thanks again. :-)