simple question of scope using a MySQL class in PHP

Question

This should be a no brainer, its late and i cant see what i am doing wrong:

MySQL class:

class MySQL
{
public $db;
private $result;

public function __construct ($host, $user, $password, $database)
{
  $this -> connectDB ($host, $user, $password, $database);
}

public function __destruct ()
{
  $this -> breakDB();
}

private function connectDB ($host, $user, $password, $database)
{
  $this -> db = mysql_connect ($host, $user, $password) or die (mysql_error());
  if (is_resource ($this -> db))
  {
    mysql_select_db ($database) or die (mysql_error());
    mysql_set_charset('utf8',$this -> db); 
  }
}

private function breakDB()
{
  if (is_resource ($this -> db))
  {
    mysql_close ($this -> db);
    }
}
}

class using MySQL:

class Scraper {
private $urls_array = array();
private $mysql;

public function __construct ()
{
        $this -> mysql = new MySQL ('xxx', 'xxx', 'xxx', 'xxx');
}
private function getURLs($city=NULL,$provider=NULL) {

    /* Get all URLs to scrape */
    $result = $this -> mysql -> db = mysql_query("SELECT `xxx`,`xxx`,`xxx`, `xxx` FROM `URL` WHERE `xxx` = '1'");
   }
   }

The line i am having probs with is:

$result = $this -> mysql -> db = mysql_query("SELECT `xxx`,`xxx`,`xxx`, `xxx` FROM `URL` WHERE `xxx` = '1'");

I dont know how to use $mysql correctly so it sends the mysql_query to the connection i opened in the constructor? Any help apreciated THANKS!

Get rid of the (') around the 1, it's bad practice to call numeric data with a char symbol. — BGPHiJACK
– BGPHiJACK, Commented Feb 22, 2011 at 1:08

Orbling · Accepted Answer · 2011-02-22 01:07:29Z

3

You just need to rearrange the line a bit:

$result = mysql_query("SELECT `xxx`,`xxx`,`xxx`, `xxx` FROM `URL` WHERE `xxx` = '1'",
                      $this -> mysql -> db);

I would suggest creating a query method in your MySQL class though and making the db private.

At its most basic:

class MySQL {
   private $db;

   // ... as before ...

   public function query($queryText) {
       return mysql_query($queryText, $this->db);
   }
}

Of course, using mysqli might be a better idea all round.

answered Feb 22, 2011 at 1:07

Orbling

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5 Comments

user142162 Over a year ago

I agree. Using mysqli or PDO is probably a better solution.

kritop Over a year ago

i use later on: mysql_real_escape_string(), can i use that too with mysqli, since its not listed as function? and mysqli seems really to be worth it :)

Orbling Over a year ago

@kritop: mysqli has the same function, mysqli::real_escape_string(). You just need to call it from the object that you create: $mysqi->real_escape_string($text)

kritop Over a year ago

using: $mysqli = new mysqli("xxx", "xxx", "xxx", "xxx"); in the constructor and later on in a function $result = $this -> mysqli->query("SELECT xxx` FROM URL WHERE scrape = 1");` leads to PHP Fatal error: Call to a member function query() on a non-object error what am i missing??

Orbling Over a year ago

@kritop: Whenever you get that error "Call to a member function...", it means whatever variable is before one of the -> is not an object, probably because you did not initialise it.

Nathan Anderson · Accepted Answer · 2011-02-22 01:15:14Z

2

You could make things a little easier on yourself by including a query function on the MySQL class you've created. The basic jist would look like this:

public function query($sqlQuery)
{
     return mysql_query($sqlQuery, $this->db);
}

You would use it like so:

$result = $this->mysql->query("SELECT `xxx`,`xxx`,`xxx`, `xxx` FROM `URL` WHERE `xxx` = '1'");

answered Feb 22, 2011 at 1:15

Nathan Anderson

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Comments

deceze · Accepted Answer · 2011-02-22 01:11:40Z

1

You would have to do this:

$result = mysql_query("SELECT ...", $this->mysql->db);

The $db property only holds the MySQL resource which you can optionally supply to the mysql functions. It would seem to make more sense if you included a query method in your MySQL class so this happens transparently and you can use $this->mysql->query('SELECT ...').

answered Feb 22, 2011 at 1:11

deceze♦

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