[SOLVED] learning OOP..please advice

[DanDaBeginner]

Hi people. im so trying to grasp the OOP approach. heres my code so far with basic mysql connection.. i need to know if im making sense when it comes to OOP approach? please need some advise..

so far heres my class code..hope it make sense..am I?  besides the error handling, what else can you advice? I know I can make the error handling more inteliigently.. am I tooo far from OOP?

<?php
class sql {
private $root;
private $un;
private $pass;
private $dbname;
private $conn;
private $query;

function __construct($root,$un,$pass,$dbname) {
	$this->root = $root;
	$this->un = $un;
	$this->pass = $pass;
	$this->dbname = $dbname;
}

function sqlConnect() {
	$conn = @mysql_connect($this->root,$this->un,$this->pass);
	if ($conn) {
		$this->conn = $conn;
	} else {
		echo 'Connection ERROR!';
	}
}

function sqlSelectDB() {
	$db = @mysql_select_db($this->dbname,$this->conn);
	if ($db) {
		return $db;
	} else {
		echo 'Connection ERROR in DATABASE!';
	}

}

function sqlQuery($query) {
	$runQuery = @mysql_query($query);
	if ($runQuery) {
		$this->query = $runQuery;
	} else {
		echo 'ERROR with query!';
	}

}

function fetch($assoc=FALSE) {
	if ($assoc) {
		$row = @mysql_fetch_assoc($this->query);
	} else {
		$row = @mysql_fetch_array($this->query);
	}
	return $row;
}
}
?>

 

and heres the example coding if im going to use this class

<?php
require_once('connect.class.php');

$new_sql = new sql('localhost','root','','testing');
$new_sql->sqlConnect();
$new_sql->sqlSelectDB();
$new_sql->sqlQuery("SELECT * FROM message");
while($row = $new_sql->fetch()) {
echo '<p>'.$row[0].'<br>FROM: '.$row[1].'<br>TO: '.$row[2].'<br>Message: '.$row[3].'<br>TimeSent: '.$row[4].'</p>';
}
?>

[Daniel0]

You should probably pass the errors to an error handler instead of directly outputting it.

[DanDaBeginner]

thanx very much Daniel0.. besides error handling, what else? am I grabbing the OOP concept here?

[per1os]

Seems like it is pretty solid code to me. Nice and simple, the way we like it.

[DanDaBeginner]

thanx very much frost110.. any one else? please!

[obsidian]

I would advise learning to use your scope declarations on your functions as a habit, too. Any functions you have that don't need to be accessible outside of your class (often those that directly modify your private variables) should be marked as private or protected as well. Also, if you ever think you will extend the class with child classes, use "protected" instead of "private" to allow those child classes access to the variables and functions within the parent class as well.

 

In addition to Daniel0's comment, I would recommend you go a step further. If you are using your "private" and "public" declarations, you must be using PHP5+, so I recommend you get into the habit of throwing errors from your classes where you can simply use a try-catch block to run things through. For instance, I would rewrite your structure slightly to allow the creation of the database class to connect and select the DB all at once. Also, this will let you do several things from one constructor call:

<?php
class sql {
protected $root;
protected $un;
protected $pass;
protected $dbname;
protected $conn;
protected $query;
protected $Debug;

public function __construct($root,$un,$pass,$dbname) {
	$this->root   = $root;
	$this->un     = $un;
	$this->pass   = $pass;
	$this->dbname = $dbname;

	$this->sqlConnect();
	$this->sqlSelectDB();
}

public function setDebug($var = true) {
	$this->Debug = $var;
}

protected function sqlConnect() {
	$conn = @mysql_connect($this->root,$this->un,$this->pass);
	if (!$conn) {
		$msg = "Could not connect to SQL server";
		if ($this->Debug) $msg .= "<br />\n" . mysql_error();
		throw new Exception($msg);
	}

	$this->conn = $conn;
}

protected function sqlSelectDB() {
	if (!@mysql_select_db($this->dbname,$this->conn)) {
		$msg = "Could not connect to database";
		if ($this->Debug) $msg .= "<br />\n" . mysql_error();
		throw new Exception($msg);
	}
}
}
?>

 

As you can see, the connect and select_db functions are both being called as part of the constructor. Also, I've added a "setDebug()" function that will tack on the mysql_error() message to the end of any Exceptions that are thrown when errors are encountered. Now, all you have to do is something like this:

<?php
try {
  $new_sql = new sql('localhost','root','','testing');
  $new_sql->setDebug(true); // Output more verbose error messages
} catch (Exception $e) {
  $error = $e->getMessage();
}

if (isset($error)) echo "<p class='error'>$error</p>\n";
?>

 

Just a little more streamlined, but you definitely are getting the idea. When you have something like the Debug I've outlined, though, be sure to always set debug to FALSE for production environments.

 

Good luck!

[per1os]

The sucky thing about those scopes is that they are only for PHP 5 and up. My server, and generally most servers that are shared run PHP 4. I am SOL on this until my server decides to update the PHP to PHP 5, which I do not see happening for a while.

 

That try and catch would be very very nice, too bad it is PHP 5 also =\ I really need to contact my server about that =)

 

 

[obsidian]

The sucky thing about those scopes is that they are only for PHP 5 and up. My server, and generally most servers that are shared run PHP 4. I am SOL on this until my server decides to update the PHP to PHP 5, which I do not see happening for a while.

 

That try and catch would be very very nice, too bad it is PHP 5 also =\ I really need to contact my server about that =)

 

Correct that it is PHP5 only. That's why I recommended it. Based on the "private" declarations in the OP, he has to be running PHP5 for that to work since those declarations are also features of OOP added in PHP5+.

[per1os]

PHP5+ is getting me more and more hooked on wanting to switch over, than my Classes will be some what an OOP "class" with protection layers etc.

 

Damn I need to do that.

[JBS103]

Just wanted to say that that is an extremely helpful post, Obsidian. Thanks a lot!

[Daniel0]

Something that would be nice for yourself to do is to make functions called update and insert that will take the name of the table and an array of the data. So you could do something like this:

$db->update("articles", array("title"=>"New title", "last_view"=>time()), "WHERE id='5'"): // Syntax: update(str $table, array $data[, str $extra]);

[per1os]

Something that would be nice for yourself to do is to make functions called update and insert that will take the name of the table and an array of the data. So you could do something like this:

$db->update("articles", array("title"=>"New title", "last_view"=>time()), "WHERE id='5'"): // Syntax: update(str $table, array $data[, str $extra]);

 

That would be pimp, thats a nice idea...now why didn't I think of that? =)

[Daniel0]

Another simple, yet useful, function would be a combination of the fetch and query function. I don't know how to explain it, so I'll give you the code:

<?php
// inside the class:
function fetch_result($query, $assoc=false)
{
$this->sqlQuery($query);

return $this->fetch($assoc);
}
?>

 

In addition to sql::sqlQuery() setting the last result in a variable, make it return it as well. (Then let sql::fetch() take it as well, and if not supplied then take the last result)

 

Edit: Oh, and you should make fetching to an associative array default instead, as that is probably what you'd be using most times.

[obsidian]

Excellent, excellent suggestions, Daniel0! There are so many things that you can do with custom DB classes to make your life simpler. One of the things I've done is in a config file, preload all your table names with pseudonyms in a definition array, and then just do all your SQL statements using the pseudonyms. This way, when you run your query, you can do a str_replace() and get all the actual table names pasted in place. How is that useful? Well, if you're looking to install your app on numerous servers, it's not a bad idea to let your client choose a table prefix for your install (in case it's being installed in the same DB as another app). This way, your table names only have to be update in one page of the code, and the class does all the rest of the work.

[per1os]

Obsidian, can you post that code? What I am wondering is how you setup the pseudonyms to be replaced, something like this?

 

$pseudoArr = array("%USERS%", "%TEMP%");
$tableArr = array("tbl_users", "tbl_template");
// then in the function after the $sql is passed you do this?

$sql = str_replace($pseudoArr, $tableArr, $sql);

// then do query running below

 

I always wanted to do it but I could never think of an efficient way to set that up or make it easier than what I was previously doing.

[DanDaBeginner]

thanx to all of you guys... really help me a lot..